0001564590-21-053473 | 10-Q | XBRL Viewer | Martin Marietta Materials INC

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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2021	Oct. 28, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	MLM
Entity Registrant Name	MARTIN MARIETTA MATERIALS, INC.
Entity Central Index Key	0000916076
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock (Par Value $0.01)
Security Exchange Name	NYSE
Entity File Number	1-12744
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	NC
Entity Tax Identification Number	56-1848578
Entity Address, Address Line One	4123 Parklake Avenue
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27612
City Area Code	919
Local Phone Number	781-4550
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		62,381,891

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 2,381.4	$ 207.3
Restricted cash	1.7	97.1
Accounts receivable, net	801.9	575.1
Inventories, net	717.5	709.0
Other current assets	98.2	79.8
Total Current Assets	4,000.7	1,668.3
Property, plant and equipment	9,536.9	8,955.0
Allowances for depreciation, depletion and amortization	(3,926.4)	(3,712.7)
Net property, plant and equipment	5,610.5	5,242.3
Goodwill	2,610.6	2,414.0
Other intangibles, net	787.2	508.0
Operating lease right-of-use assets, net	417.8	453.0
Other noncurrent assets	359.4	295.2
Total Assets	13,786.2	10,580.8
Current Liabilities:
Accounts payable	249.3	207.8
Accrued salaries, benefits and payroll taxes	65.5	82.6
Accrued other taxes	59.4	45.4
Current maturities of long-term debt and short-term facilities	20.1
Accrued interest	46.1	18.3
Operating lease liabilities	47.3	48.6
Other current liabilities	113.5	96.6
Total Current Liabilities	601.2	499.3
Long-term debt	5,099.4	2,625.8
Deferred income taxes, net	809.3	781.5
Noncurrent operating lease liabilities	375.9	410.4
Other noncurrent liabilities	542.2	370.5
Total Liabilities	7,428.0	4,687.5
Equity:
Common stock, par value $0.01 per share (62.4 and 62.3 shares outstanding at September 30, 2021 and December 31, 2020, respectively)	0.6	0.6
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,463.3	3,440.8
Accumulated other comprehensive loss	(151.4)	(158.4)
Retained earnings	3,043.4	2,607.7
Total Shareholders' Equity	6,355.9	5,890.7
Noncontrolling interests	2.3	2.6
Total Equity	6,358.2	5,893.3
Total Liabilities and Equity	$ 13,786.2	$ 10,580.8

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares, outstanding	62.4	62.3
Preferred stock, par value	$ 0.01	$ 0.01

Consolidated Statements of Earnings and Comprehensive Earnings (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Total Revenues	$ 1,557.3	$ 1,321.4	$ 3,917.6	$ 3,550.3
Total Cost of Revenues	1,115.4	916.9	2,915.9	2,622.9
Gross Profit	441.9	404.5	1,001.7	927.4
Selling, general & administrative expenses	86.0	71.1	248.2	221.0
Acquisition-related expenses	7.4	0.4	18.0	1.2
Other operating income, net	(8.4)	(67.6)	(28.2)	(59.6)
Earnings from Operations	356.9	400.6	763.7	764.8
Interest expense	44.3	28.7	99.9	89.7
Other nonoperating income, net	(5.6)	(4.0)	(23.8)	(5.9)
Earnings before income tax expense	318.2	375.9	687.6	681.0
Income tax expense	63.6	81.5	141.7	143.0
Consolidated net earnings	254.6	294.4	545.9	538.0
Less: Net earnings attributable to noncontrolling interests			0.2
Net Earnings Attributable to Martin Marietta Materials, Inc.	254.6	294.4	545.7	538.0
Consolidated Comprehensive Earnings:
Earnings attributable to Martin Marietta Materials, Inc.	256.2	298.0	552.7	545.2
Earnings attributable to noncontrolling interests			0.2
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 256.2	$ 298.0	$ 552.9	$ 545.2
Net Earnings Attributable to Martin Marietta Materials, Inc. Per Common Share:
Basic attributable to common shareholders	$ 4.08	$ 4.72	$ 8.74	$ 8.63
Diluted attributable to common shareholders	$ 4.07	$ 4.71	$ 8.72	$ 8.61
Weighted-Average Common Shares Outstanding:
Basic	62.4	62.3	62.4	62.3
Diluted	62.6	62.4	62.6	62.4
Products and Services
Total Revenues	$ 1,462.7	$ 1,240.7	$ 3,679.9	$ 3,321.2
Total Cost of Revenues	1,021.0	836.1	2,676.9	2,390.9
Freight
Total Revenues	94.6	80.7	237.7	229.1
Total Cost of Revenues	$ 94.4	$ 80.8	$ 239.0	$ 232.0

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows from Operating Activities:
Consolidated net earnings	$ 545.9	$ 538.0
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	320.0	292.2
Stock-based compensation expense	33.0	22.4
Gain on divestitures and sales of assets	(26.6)	(71.2)
Deferred income taxes	25.7	24.8
Other items, net	(8.3)	0.8
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(218.0)	(104.5)
Inventories, net	65.1	(22.6)
Accounts payable	66.9	(0.8)
Other assets and liabilities, net	(23.4)	4.9
Net Cash Provided by Operating Activities	780.3	684.0
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(321.3)	(250.8)
Acquisitions, net of cash acquired	(792.9)	(64.0)
Proceeds from divestitures and sales of assets	41.4	141.2
Investments in life insurance contracts, net	13.9	(12.7)
Other investing activities, net		(5.4)
Net Cash Used for Investing Activities	(1,058.9)	(191.7)
Cash Flows from Financing Activities:
Borrowings of debt	2,896.6	628.1
Repayments of debt	(400.0)	(777.0)
Payments on financing leases	(7.6)	(2.3)
Debt issuance costs	(6.1)	(2.0)
Distributions to owners of noncontrolling interest	(0.5)
Repurchases of common stock		(50.0)
Dividends paid	(109.7)	(104.8)
Proceeds from exercise of stock options	1.1	1.4
Shares withheld for employees' income tax obligations	(16.5)	(13.0)
Net Cash Provided by (Used for) Financing Activities	2,357.3	(319.6)
Net Increase in Cash, Cash Equivalents and Restricted Cash	2,078.7	172.7
Cash, Cash Equivalents and Restricted Cash, beginning of period	304.4	21.0
Cash, Cash Equivalents and Restricted Cash, end of period	$ 2,383.1	$ 193.7

Consolidated Statements of Total Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total Shareholders' Equity	Noncontrolling Interests
Beginning Balance at Dec. 31, 2019	$ 5,353.3	$ 0.6	$ 3,418.8	$ (145.8)	$ 2,077.2	$ 5,350.8	$ 2.5
Beginning Balance (in shares) at Dec. 31, 2019		62.4
Consolidated net earnings	538.0				538.0	538.0
Other comprehensive earnings, net of tax	7.2			7.2		7.2
Dividends declared	(104.7)				(104.7)	(104.7)
Issuances of common stock for stock award plans	5.7		5.7			5.7
Issuances of common stock for stock award plans (in shares)		0.1
Shares withheld for employees' income tax obligations	(13.0)		(13.0)			(13.0)
Repurchases of common stock	(50.0)				(50.0)	(50.0)
Repurchases of common stock, Shares		(0.2)
Stock-based compensation expense	22.4		22.4			22.4
Ending Balance at Sep. 30, 2020	5,758.9	$ 0.6	3,433.9	(138.6)	2,460.5	5,756.4	2.5
Ending Balance (in shares) at Sep. 30, 2020		62.3
Beginning Balance at Jun. 30, 2020	5,493.6	$ 0.6	3,431.0	(142.2)	2,201.7	5,491.1	2.5
Beginning Balance (in shares) at Jun. 30, 2020		62.3
Consolidated net earnings	294.4				294.4	294.4
Other comprehensive earnings, net of tax	3.6			3.6		3.6
Dividends declared	(35.6)				(35.6)	(35.6)
Issuances of common stock for stock award plans	0.2		0.2			0.2
Stock-based compensation expense	2.7		2.7			2.7
Ending Balance at Sep. 30, 2020	5,758.9	$ 0.6	3,433.9	(138.6)	2,460.5	5,756.4	2.5
Ending Balance (in shares) at Sep. 30, 2020		62.3
Beginning Balance at Dec. 31, 2020	$ 5,893.3	$ 0.6	3,440.8	(158.4)	2,607.7	5,890.7	2.6
Beginning Balance (in shares) at Dec. 31, 2020	62.3	62.3
Consolidated net earnings	$ 545.9				545.7	545.7	0.2
Other comprehensive earnings, net of tax	7.0			7.0		7.0
Dividends declared	(110.0)				(110.0)	(110.0)
Issuances of common stock for stock award plans	6.0		6.0			6.0
Issuances of common stock for stock award plans (in shares)		0.1
Shares withheld for employees' income tax obligations	(16.5)		(16.5)			(16.5)
Stock-based compensation expense	33.0		33.0			33.0
Distributions to owners of noncontrolling interest	(0.5)						(0.5)
Ending Balance at Sep. 30, 2021	$ 6,358.2	$ 0.6	3,463.3	(151.4)	3,043.4	6,355.9	2.3
Ending Balance (in shares) at Sep. 30, 2021	62.4	62.4
Beginning Balance at Jun. 30, 2021	$ 6,128.2	$ 0.6	3,451.1	(153.0)	2,827.2	6,125.9	2.3
Beginning Balance (in shares) at Jun. 30, 2021		62.4
Consolidated net earnings	254.6				254.6	254.6
Other comprehensive earnings, net of tax	1.6			1.6		1.6
Dividends declared	(38.4)				(38.4)	(38.4)
Issuances of common stock for stock award plans	0.4		0.4			0.4
Shares withheld for employees' income tax obligations	(0.4)		(0.4)			(0.4)
Stock-based compensation expense	12.2		12.2			12.2
Ending Balance at Sep. 30, 2021	$ 6,358.2	$ 0.6	$ 3,463.3	$ (151.4)	$ 3,043.4	$ 6,355.9	$ 2.3
Ending Balance (in shares) at Sep. 30, 2021	62.4	62.4

Consolidated Statements of Total Equity (Parenthetical) (Unaudited) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Stockholders Equity [Abstract]
Dividends declared	$ 0.61	$ 0.57	$ 1.75	$ 1.67

Significant Accounting Policies

9 Months Ended

Sep. 30, 2021

Accounting Policies [Abstract]

Significant Accounting Policies

1.	Significant Accounting Policies

Organization

Martin Marietta Materials, Inc. (the Company or Martin Marietta) is a natural resource-based building materials company. As of September 30, 2021, the Company supplies aggregates (crushed stone, sand and gravel) through its network of approximately 320 quarries, mines and distribution yards in 26 states, Canada and The Bahamas. In the southwestern and western United States, Martin Marietta also provides cement and downstream products and services, namely, ready mixed concrete, asphalt and paving, in vertically-integrated structured markets where the Company has a leading aggregates position. The Company’s heavy-side building materials are used in infrastructure, nonresidential and residential construction projects. Aggregates are also used in agricultural, utility and environmental applications and as railroad ballast. The aggregates, cement, ready mixed concrete, asphalt and paving product lines are reported collectively as the “Building Materials” business.

The Company’s Building Materials business includes two reportable segments: the East Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	East Group	West Group
Operating Locations	Alabama, Florida, Georgia, Indiana, Iowa, Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, Nova Scotia and The Bahamas	Arkansas, Colorado, Louisiana, western Nebraska, Oklahoma, Texas, Utah, Washington and Wyoming

Product Lines	Aggregates and Asphalt	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

The Company’s Magnesia Specialties business, which represents a separate reportable segment, has manufacturing facilities in Manistee, Michigan, and Woodville, Ohio. The Magnesia Specialties business produces magnesia-based chemicals products used in industrial, agricultural and environmental applications, and dolomitic lime sold primarily to customers in the steel and mining industries.

Basis of Presentation

The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) for interim financial information and with the instructions to the Quarterly Report on Form 10-Q and in Article 10 of Regulation S-X. The Company has continued to follow the accounting policies set forth in the audited consolidated financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. In the opinion of management, the interim consolidated financial information provided herein reflects all adjustments, consisting of normal recurring accruals, necessary for a fair statement of the results of operations, financial position and cash flows for the interim periods. The consolidated results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results expected for other interim periods or the full year. The consolidated balance sheet at December 31, 2020 has been derived from the audited consolidated financial statements at that date but does not include all of the information and notes required by U.S. GAAP for complete financial statements. These consolidated financial statements should be read in conjunction with the audited

consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

The preparation of the Company’s consolidated financial statements requires management to make certain estimates and assumptions about future events. As future events and their effects cannot be fully determined with precision, actual results could differ significantly from estimates. Changes in estimates are reflected in the consolidated financial statements in the period in which the change in estimate occurs.

Reclassifications

As of January 1, 2021, the Company reclassified accrued income taxes from Other current liabilities to Accrued other taxes on the Company’s consolidated balance sheet. Prior-year information has been reclassified to conform to current year presentation. The reclassification had no impact on the Company’s previously reported results of operations, financial position or cash flows.

Consolidated Comprehensive Earnings and Accumulated Other Comprehensive Loss

Consolidated comprehensive earnings and accumulated other comprehensive loss consist of consolidated net earnings; adjustments for the funded status of pension and postretirement benefit plans; and foreign currency translation adjustments; and are presented in the Company’s consolidated statements of earnings and comprehensive earnings.

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(Dollars in Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Other comprehensive earnings, net of tax		1.6		3.6		7.0		7.2
Comprehensive earnings attributable to Martin Marietta	$	256.2	$	298.0	$	552.7	$	545.2

Changes in accumulated other comprehensive loss, net of tax, are as follows:

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Three Months Ended September 30, 2021
Balance at beginning of period	$	(153.5	)	$	0.5		$	(153.0	)
Other comprehensive loss before reclassifications, net of tax		—			(0.6	)		(0.6	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.2			—			2.2
Other comprehensive earnings (loss), net of tax		2.2			(0.6	)		1.6
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Three Months Ended September 30, 2020
Balance at beginning of period	$	(140.0	)	$	(2.2	)	$	(142.2	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		3.1			—			3.1
Other comprehensive earnings, net of tax		3.1			0.5			3.6
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Nine Months Ended September 30, 2021
Balance at beginning of period	$	(158.1	)	$	(0.3	)	$	(158.4	)
Other comprehensive earnings before reclassifications, net of tax		—			0.2			0.2
Amounts reclassified from accumulated other comprehensive loss, net of tax		6.8			—			6.8
Other comprehensive earnings, net of tax		6.8			0.2			7.0
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Nine Months Ended September 30, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(0.8	)		(0.8	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		8.0			—			8.0
Other comprehensive earnings (loss), net of tax		8.0			(0.8	)		7.2
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

Changes in net noncurrent deferred tax assets related to accumulated other comprehensive loss are as follows:

	Pension and Postretirement Benefit Plans
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Balance at beginning of period	$	87.9		$	83.6		$	89.4		$	85.2
Tax effect of other comprehensive earnings		(0.8	)		(1.1	)		(2.3	)		(2.7	)
Balance at end of period	$	87.1		$	82.5		$	87.1		$	82.5

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Nine Months Ended						Affected line items in the
	September 30,						September 30,						consolidated statements of earnings
	2021			2020			2021			2020			and comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	—		$	—		$	(0.1	)
Actuarial loss		3.0			4.2			9.1			10.8		Other nonoperating income, net
		3.0			4.2			9.1			10.7
Tax benefit		(0.8	)		(1.1	)		(2.3	)		(2.7	)	Income tax expense
	$	2.2		$	3.1		$	6.8		$	8.0

Earnings per Common Share

The numerator for basic and diluted earnings per common share is net earnings attributable to Martin Marietta reduced by dividends and undistributed earnings attributable to certain of the Company’s stock-based compensation. If there is a net loss, no amount of the undistributed loss is attributed to unvested participating securities. The denominator for basic earnings per common share is the weighted-average number of common shares outstanding during the period. Diluted earnings per common share are computed assuming that the weighted-average number of common shares is increased by the conversion, using the treasury stock method, of awards to be issued to employees and nonemployee members of the Company’s Board of Directors under certain stock-based compensation arrangements if the conversion is dilutive. For the three and nine months ended September 30, 2021 and 2020, the diluted per-share computations reflect the number of common shares outstanding to include the number of additional shares that would have been outstanding if the potentially dilutive common shares had been issued.

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(In Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.3		—		0.5
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta	$	254.6	$	294.1	$	545.7	$	537.5

Basic weighted-average common shares outstanding		62.4		62.3		62.4		62.3
Effect of dilutive employee and director awards		0.2		0.1		0.2		0.1
Diluted weighted-average common shares outstanding		62.6		62.4		62.6		62.4

Restricted Cash

At September 30, 2021 and December 31, 2020, the Company had restricted cash of $1.7 million and $97.1 million, respectively, which is invested in an account designated for the purchase of like-kind exchange replacement assets under Section 1031 of the Internal Revenue Code and related IRS procedures (Section 1031). The Company is restricted from utilizing the cash for purposes other than the purchase of the qualified assets for a designated period from receipt of the proceeds from the sale of the exchanged property. Any unused cash at the end of the designated period will be transferred to unrestricted accounts of the Company and can then be used for general corporate purposes. The Company has until January 10, 2022 to use the remaining restricted cash to purchase qualified assets under Section 1031.

In connection with Accounting Standards Update 2016-18, Statement of Cash Flows (Topic 230), the statement of cash flows reflects cash flow changes and balances for cash, cash equivalents and restricted cash on an aggregated basis.

The following table reconciles cash, cash equivalents and restricted cash as reported on the consolidated balance sheets to the aggregated amounts presented on the consolidated statements of cash flows:

	September 30,		December 31,
	2021		2020
	(Dollars in Millions)
Cash and cash equivalents	$	2,381.4	$	207.3
Restricted cash		1.7		97.1
Total cash, cash equivalents and restricted cash presented in the consolidated statements of cash flows	$	2,383.1	$	304.4

New Accounting Pronouncement

In March 2020, the FASB issued Accounting Standards Update (ASU) 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting”, an optional guidance for a limited period of time to ease the transition from the London interbank offered rate (“LIBOR”) to an alternative reference rate. The

ASU intends to address certain concerns relating to accounting for contract modifications and hedge accounting. These optional expedients and exceptions to applying U.S. GAAP, assuming certain criteria are met, are allowed through December 31, 2022, and any amendments should be applied on a prospective basis. The Company does not expect the transition from LIBOR to have a material impact on its consolidated financial statements.

Revenue Recognition

9 Months Ended

Sep. 30, 2021

Revenue From Contract With Customer [Abstract]

Revenue Recognition

2.	Revenue Recognition

Total revenues include sales of products and services to customers, net of any discounts or allowances, and freight revenues. Product revenues are recognized when control of the promised good is transferred to the customer, typically when finished products are shipped. Intersegment and interproduct revenues are eliminated in consolidation. Service revenues are derived from the paving business and are recognized using the percentage-of-completion method under the cost-to-cost approach. Freight revenues reflect delivery arranged by the Company using a third party on behalf of the customer and are recognized consistently with the timing of the product revenues.

Performance Obligations. Performance obligations are contractual promises to transfer or provide a distinct good or service for a stated price. The Company’s product sales agreements are single-performance obligations that are satisfied at a point in time. Performance obligations within paving service agreements are satisfied over time, primarily ranging from one day to two years. For product revenues and freight revenues, customer payment terms are generally 30 days from invoice date. Customer payments for the paving operations are based on a contractual billing schedule and are due 30 days from invoice date.

Future revenues from unsatisfied performance obligations at September 30, 2021 and 2020 were $183.0 million and $150.2 million, respectively, where the remaining periods to complete these obligations ranged from one month to 21 months and one month to 13 months, respectively.

Revenue by Category. The following table presents the Company’s total revenues by category for each reportable segment.

	Three Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	641.8	$	42.3	$	684.1
West Group		749.0		45.8		794.8
Total Building Materials business		1,390.8		88.1		1,478.9
Magnesia Specialties		71.9		6.5		78.4
Total	$	1,462.7	$	94.6	$	1,557.3

	Three Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	514.1	$	35.2	$	549.3
West Group		671.4		39.8		711.2
Total Building Materials business		1,185.5		75.0		1,260.5
Magnesia Specialties		55.2		5.7		60.9
Total	$	1,240.7	$	80.7	$	1,321.4

Service revenues, which include paving services located in Colorado , were $100.5 million and $112.8 million for the three months ended September 30, 2021 and 2020, respectively, and are reported in the West Group .

	Nine Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,610.9	$	103.5	$	1,714.4
West Group		1,861.9		116.3		1,978.2
Total Building Materials business		3,472.8		219.8		3,692.6
Magnesia Specialties		207.1		17.9		225.0
Total	$	3,679.9	$	237.7	$	3,917.6

	Nine Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,371.8	$	94.1	$	1,465.9
West Group		1,785.4		118.8		1,904.2
Total Building Materials business		3,157.2		212.9		3,370.1
Magnesia Specialties		164.0		16.2		180.2
Total	$	3,321.2	$	229.1	$	3,550.3

Service revenues for the nine months ended September 30, 2021 and 2020 were $182.7 million and $221.3 million, respectively.

Contract Balances. Costs in excess of billings relate to the conditional right to consideration for completed contractual performance and are contract assets on the consolidated balance sheets. Costs in excess of billings are reclassified to accounts receivable when the right to consideration becomes unconditional. Billings in excess of costs relate to customers invoiced in advance of contractual performance and are contract liabilities on the consolidated balance sheets. The following table presents information about the Company’s contract balances:

(Dollars in Millions)	September 30, 2021		December 31, 2020
Costs in excess of billings	$	10.8	$	2.2
Billings in excess of costs	$	10.7	$	14.0

Revenues recognized from the beginning balance of contract liabilities for the three months ended September 30, 2021 and 2020 were $7.1 million and $8.5 million, respectively, and for the nine months ended September 30, 2021 and 2020 were $11.9 million and $7.2 million, respectively.

Retainage, which primarily relates to the paving services, represents amounts that have been billed to customers but payment withheld until final acceptance by the customer of the performance obligation. Included in other current assets on the Company’s consolidated balance sheets, retainage was $10.0 million and $10.6 million at September 30, 2021 and December 31, 2020, respectively.

Policy Elections. When the Company arranges third-party freight to deliver products to customers, the Company has elected the delivery to be a fulfillment activity rather than a separate performance obligation. Further, the

Company acts as a principal in the delivery arrangements and, as required by the accounting standard, the related revenues and costs are presented gross and are included in the consolidated statements of earnings.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Paragraph 10
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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+ Details

Business Combinations

9 Months Ended

Sep. 30, 2021

Business Combinations [Abstract]

Business Combinations

3.	Business Combinations

On July 30, 2021, the Company acquired assets of Southern Crushed Concrete (SCC). SCC is a leading producer of recycled concrete in the Houston area, one of the country’s largest addressable aggregates markets. Recycled concrete is principally used as a base aggregates product in infrastructure, commercial and residential construction applications. The Company acquired inventories; property, plant and equipment; intangible assets (including goodwill), and right-of-use assets; and assumed asset retirement obligations; lease obligations; and other liabilities. The goodwill generated by the transaction will be deductible for income tax purposes. Although the initial accounting for the business combination has been recorded, the fair values of these amounts are subject to change during the measurement period, which remains open as of September 30, 2021. The acquisition is reported in the Company’s West Group, but is immaterial for pro-forma financial statement disclosures.

On April 30, 2021, the Company completed the acquisition of Tiller Corporation (Tiller), a leading aggregates and hot mix asphalt supplier in the Minneapolis/St. Paul area, one of the largest and fastest growing midwestern metropolitan areas. The Tiller acquisition complements the Company’s existing product offerings in the surrounding areas. Additionally, Tiller sells asphalt solely as a materials provider and does not offer paving or other associated services. The Company financed the acquisition using available cash and borrowings under its credit facilities. The Company has recorded preliminary fair values of the assets acquired and liabilities assumed, which are subject to asset verification and a normal post-closing working capital adjustment. Therefore, the measurement period for property, plant and equipment and goodwill remains open as of September 30, 2021. The goodwill generated by the transaction will be deductible for income tax purposes. The acquisition is reported in the Company’s East Group, but is immaterial for pro-forma financial statement disclosures.

Goodwill and Other Intangibles

9 Months Ended

Sep. 30, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangibles

4.	Goodwill and Other Intangibles

The following table shows the changes in goodwill by reportable segment and in total:

	East		West
	Group		Group			Total
	(Dollars in Millions)
Balance at January 1, 2021	$	572.5	$	1,841.5		$	2,414.0
Acquisitions		185.9		12.8			198.7
Goodwill allocated to assets held for sale		—		(2.1	)		(2.1	)
Balance at September 30, 2021	$	758.4	$	1,852.2		$	2,610.6

Intangible assets subject to amortization consist of the following:

	Gross Amount		Accumulated Amortization			Net Balance
(Dollars in Millions)	September 30, 2021
Noncompetition agreements	$	4.2	$	(4.1	)	$	0.1
Customer relationships		312.7		(44.3	)		268.4
Operating permits		523.8		(53.7	)		470.1
Use rights and other		16.4		(13.8	)		2.6
Trade names		23.3		(13.3	)		10.0
Total	$	880.4	$	(129.2	)	$	751.2

	December 31, 2020
Noncompetition agreements	$	4.2	$	(4.1	)	$	0.1
Customer relationships		91.3		(35.6	)		55.7
Operating permits		460.8		(48.4	)		412.4
Use rights and other		16.3		(13.0	)		3.3
Trade names		12.8		(12.3	)		0.5
Total	$	585.4	$	(113.4	)	$	472.0

At September 30, 2021 and December 31, 2020, intangible assets deemed to have an indefinite life and not being amortized consist of the following:

(Dollars in Millions)	Building Materials business		Magnesia Specialties		Total
Operating permits	$	6.6	$	—	$	6.6
Use rights		26.7		—		26.7
Trade names		0.2		2.5		2.7
Total	$	33.5	$	2.5	$	36.0

For the nine months ended September 30, 2021, the Company acquired $294.9 million of intangibles, which consists of the following:

(Dollars in Millions)	Amount		Weighted-average amortization period
Subject to amortization:
Customer relationships	$	221.4	24 years
Permits		63.0	40 years
Trade name		10.5	9 years
Total	$	294.9	27 years

Total amortization expense for intangible assets for the nine months ended September 30, 2021 and 2020 was $15.2 million and $9.8 million, respectively.

The estimated amortization expense for intangibles for the remainder of 2021, each of the next four years, and thereafter is as follows:

(Dollars in Millions)
October - December 2021	$	6.4
2022		25.0
2023		24.7
2024		24.4
2025		24.3
Thereafter		646.4
Total	$	751.2

Inventories, Net

9 Months Ended

Sep. 30, 2021

Inventory Disclosure [Abstract]

Inventories, Net

5.	Inventories, Net

	September 30,			December 31,
	2021			2020
	(Dollars in Millions)
Finished products	$	683.2		$	667.0
Products in process		25.6			37.1
Raw materials		55.9			35.3
Supplies and expendable parts		152.0			149.9
		916.7			889.3
Less: Allowances		(199.2	)		(180.3	)
Total	$	717.5		$	709.0

Long-Term Debt

9 Months Ended

Sep. 30, 2021

Debt Disclosure [Abstract]

Long-Term Debt

6.	Long-Term Debt

	September 30,			December 31,
	2021			2020
	(Dollars in Millions)
0.650% Senior Notes, due 2023	$	696.9		$	—
4.250% Senior Notes, due 2024		398.1			397.6
7% Debentures, due 2025		124.5			124.5
3.450% Senior Notes, due 2027		297.9			297.6
3.500% Senior Notes, due 2027		496.2			495.8
2.500% Senior Notes, due 2030		490.9			490.1
2.400% Senior Notes, due 2031		891.7			—
6.25% Senior Notes, due 2037		228.3			228.2
4.250% Senior Notes, due 2047		592.0			591.9
3.200% Senior Notes, due 2051		882.9			—
Trade Receivable Facility, interest rate of 0.77 % at September 30, 2021		20.0			—
Other notes		0.1			0.1
Total debt		5,119.5			2,625.8
Less: Current maturities of long-term debt		(20.1	)		—
Long-term debt	$	5,099.4		$	2,625.8

On July 2, 2021, the Company issued $700 million aggregate principal amount of 0.650% Senior Notes due 2023 (the 0.650% Senior Notes), $900 million aggregate principal amount of 2.400% Senior Notes due 2031 (the 2.400% Senior Notes) and $900 million aggregate principal amount of 3.200% Senior Notes due 2051 (the 3.200% Senior Notes) and, together with the 0.650% Senior Notes and the 2.400% Senior Notes (the Senior Notes), pursuant to a base indenture, dated as of May 22, 2017 (the Base Indenture), as amended and supplemented from time to time, including by the Fourth Supplemental Indenture, dated as of July 2, 2021 and, together with the Base Indenture (the Indenture) between the Company and Regions Bank, as trustee, governing the Senior Notes. The Senior Notes are carried net of original issue discount, which will be amortized using the effective interest method over the lives of the issues. The Company used the net proceeds of the 2.400% Senior Notes, the 3.200% Senior Notes and the 0.650% Senior Notes to pay the consideration for the acquisition of Lehigh Hanson, Inc.’s West Region (Lehigh West Region) business, and for general corporate purposes. See Note 16 for more information on the Lehigh West Region acquisition, which was consummated on October 1, 2021.

Prior to July 2, 2022 (the 2023 Par Call Date), the Company may redeem the 0.650% Senior Notes, at its option, at any time in whole or from time to time in part at a price equal to the greater of: (i) 100% of the principal amount of the 0.650% Senior Notes to be redeemed and (ii) the sum of the present values of the principal amount of the 0.650% Senior Notes to be redeemed and the remaining scheduled payments of interest thereon after the date of optional redemption (a 2023 Optional Redemption Date) through the 2023 Par Call Date (assuming, for this purpose, that the 0.650% Senior Notes are scheduled to mature on the 2023 Par Call Date), excluding interest, if any, accrued thereon to such 2023 Optional Redemption Date, discounted to such 2023 Optional Redemption Date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the Indenture) plus 10 basis points (or 0.100%) plus, in each case, unpaid interest, if any, accrued thereon to, but excluding, such 2023 Optional Redemption Date. On or after the 2023 Par Call Date and prior to maturity, the Company may redeem the 0.650% Senior Notes at any time in whole or from time to time in part at a price equal to 100% of the principal amount of the 0.650% Senior Notes, at its option, to be redeemed, plus unpaid interest, if any, accrued thereon to, but excluding, the 2023 Optional Redemption Date.

Prior to April 15, 2031 (the 2031 Par Call Date), the Company may redeem the 2.400% Senior Notes, at its option, at any time in whole or from time to time in part at a price equal to the greater of: (i) 100% of the principal amount of the 2.400% Senior Notes to be redeemed and (ii) the sum of the present values of the principal amount of the 2.400% Senior Notes to be redeemed and the remaining scheduled payments of interest thereon after the date of optional redemption (a 2031 Optional Redemption Date) through the 2031 Par Call Date (assuming, for this purpose, that the 2.400% Senior Notes are scheduled to mature on the 2031 Par Call Date), excluding interest, if any, accrued thereon to such 2031 Optional Redemption Date, discounted to such 2031 Optional Redemption Date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the Indenture) plus 15 basis points (or 0.150%) plus, in each case, unpaid interest, if any, accrued thereon to, but excluding, such 2031 Optional Redemption Date. On or after the 2031 Par Call Date and prior to maturity, the Company may redeem the 2.400% Senior Notes at any time in whole or from time to time in part at a price equal to 100% of the principal amount of the 2.400% Senior Notes, at its option, to be redeemed, plus unpaid interest, if any, accrued thereon to, but excluding, the 2031 Optional Redemption Date.

Prior to January 15, 2051 (the 2051 Par Call Date), the Company may redeem the 3.200% Senior Notes, at its option, at any time in whole or from time to time in part at a price equal to the greater of: (i) 100% of the principal amount of the 3.200% Senior Notes to be redeemed and (ii) the sum of the present values of the principal amount of the 3.200% Senior Notes to be redeemed and the remaining scheduled payments of interest thereon after the date of optional redemption (a 2051 Optional Redemption Date) through the 2051 Par Call Date (assuming, for this purpose, that the 3.200% Senior Notes are scheduled to mature on the 2051 Par Call Date), excluding interest, if any, accrued thereon to such 2051 Optional Redemption Date, discounted to such 2051 Optional Redemption Date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the Indenture) plus 20 basis points (or 0.200%) plus, in each case, unpaid interest, if any, accrued thereon to, but excluding, such 2051 Optional Redemption Date. On or after the 2051 Par Call Date and prior to maturity, the Company may redeem the 3.200% Senior Notes at any time in whole or from time to time in part at a price equal to 100% of the principal amount of the 3.200% Senior Notes, at its option, to be redeemed, plus unpaid interest, if any, accrued thereon to, but excluding, the 2051 Optional Redemption Date.

The Company, through a wholly-owned special-purpose subsidiary, has a $400 million trade receivable securitization facility (the Trade Receivable Facility). On September 22, 2021 the Company extended the maturity to September 21, 2022. The Trade Receivable Facility, with Truist Bank, Regions Bank, PNC Bank, N.A., The Bank of Tokyo-Mitsubishi UFJ, LTD. (New York Branch), and certain other lenders that may become a party to the facility from time to time, is backed by eligible trade receivables, as defined, and is limited to the lesser of the facility limit or the borrowing base, as defined. These receivables are originated by the Company and then sold by the Company to the wholly-owned special-purpose subsidiary. The Company continues to be responsible for the servicing and administration of the receivables purchased by the wholly-owned special-purpose subsidiary. Borrowings under the Trade Receivable Facility bear interest at a rate equal to asset-backed commercial paper costs of conduit lenders plus 0.60% for borrowings funded by conduit lenders and one-month LIBOR plus 0.70%, subject to change in the event that this rate no longer reflects the lender’s cost of lending, for borrowings funded by all other lenders. The Trade Receivable Facility contains a cross-default provision to the Company’s other debt agreements. Subject to certain conditions, including lenders providing the requisite commitments, the Trade Receivable Facility may be increased to a borrowing base not to exceed $500 million. There was $20.0 million outstanding under the Trade Receivable Facility at September 30, 2021, and no borrowings outstanding at December 31, 2020.

The Company has a $700 million five-year senior unsecured revolving facility (the Revolving Facility) with JPMorgan Chase Bank, N.A., as Administrative Agent, Truist Bank, Deutsche Bank Securities, Inc., and Wells Fargo Bank, N.A., as Co-Syndication Agents, and the lenders party thereto. Borrowings under the Revolving Facility bear interest, at the Company’s option, at rates based upon LIBOR or a base rate, plus, for each rate, a margin determined in accordance with a ratings-based pricing grid. There were no borrowings outstanding under the Revolving Facility at September 30, 2021 or December 31, 2020. The Revolving Facility requires the Company’s ratio of consolidated debt-to-consolidated earnings before interest, taxes, depreciation and amortization (EBITDA), as defined by the Revolving Facility, for the trailing-twelve months (the Ratio) to not exceed 3.50x as of the end of any fiscal quarter, provided that the Company may exclude from the Ratio debt incurred in connection with certain acquisitions during such quarter or the three preceding quarters so long as the Ratio calculated without such exclusion does not exceed 3.75x. Additionally, if there are no amounts outstanding under the Revolving Facility and the Trade Receivable Facility, consolidated debt, including debt for which the Company is a co-borrower, may be reduced by the Company’s unrestricted cash and cash equivalents in excess of $50 million, such reduction not to exceed $200 million, for purposes of the covenant calculation. The Company was in compliance with this covenant at September 30, 2021.

The Revolving Facility expires on December 5, 2024, with any outstanding principal amounts, together with interest accrued thereon, due in full on that date. Available borrowings under the Revolving Facility are reduced by any

outstanding letters of credit issued by the Company under the Revolving Facility. The Company had $2.6 million of outstanding letters of credit issued under the Revolving Facility at September 30, 2021 and December 31, 2020.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Financial Instruments

9 Months Ended

Sep. 30, 2021

Financial Instruments Disclosure [Abstract]

Financial Instruments

7.	Financial Instruments

The Company’s financial instruments include temporary cash investments, restricted cash, accounts receivable, accounts payable, publicly-registered long-term notes, debentures and other long-term debt. The estimated fair values for all financial instruments are estimated based on Level 2 of the fair value hierarchy.

Temporary cash investments are placed primarily in money market funds, money market demand deposit accounts and Eurodollar time deposits. The Company’s cash equivalents have original maturities of less than three months. Due to the short maturity of these investments, they are carried on the consolidated balance sheets at cost, which approximates fair value.

Restricted cash is held in a trust account with a third-party intermediary. Due to the short-term nature of this account, the fair value of restricted cash approximates its carrying value.

Accounts receivable are due from a large number of customers, primarily in the construction industry, and are dispersed across wide geographic and economic regions. No single customer accounted for 10% or more of consolidated total revenues in the three-month and nine-month periods ended September 30, 2021 and 2020. The estimated fair values of accounts receivable approximate their carrying amounts due to the short-term nature of the accounts.

Accounts payable represent amounts owed to suppliers and vendors. The estimated fair value of accounts payable approximates the carrying amount due to the short-term nature of the payables.

The carrying values and fair values of the Company’s long-term debt were $5.12 billion and $5.49 billion, respectively, at September 30, 2021 and $2.63 billion and $3.08 billion, respectively, at December 31, 2020. The estimated fair value of the publicly-registered long-term notes was estimated using quoted market prices. The estimated fair values of other borrowings approximate their carrying amounts as the interest rates reset periodically.

Income Taxes

9 Months Ended

Sep. 30, 2021

Income Tax Disclosure [Abstract]

Income Taxes

8.	Income Taxes

The effective income tax rate reflects the effect of federal and state income taxes on earnings and the impact of differences in book and tax accounting arising primarily from the permanent tax benefits associated with the statutory depletion deduction for mineral reserves. For the nine months ended September 30, 2021, the effective income tax rate was 20.6%, which included a $2.9 million discrete benefit for research and development tax credits. For the nine months ended September 30, 2020, the effective income tax rate of 21.0% reflected a $6.9 million discrete benefit from financing third-party railroad track maintenance. In exchange, the Company received a federal income tax credit and deduction.

The Company records interest accrued in relation to unrecognized tax benefits as income tax expense. Penalties, if incurred, are recorded as operating expenses in the consolidated statements of earnings and comprehensive earnings.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Pension and Postretirement Benefits

9 Months Ended

Sep. 30, 2021

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

9.	Pension and Postretirement Benefits

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Service cost	$	11.6		$	9.8		$	—		$	—
Interest cost		8.9			9.3			0.1			0.1
Expected return on assets		(17.7	)		(15.2	)		—			—
Amortization of:
Prior service cost (credit)		0.2			0.2			(0.2	)		(0.2	)
Actuarial loss		3.0			4.2			—			—
Net periodic benefit cost (credit)	$	6.0		$	8.3		$	(0.1	)	$	(0.1	)

	Pension						Postretirement Benefits
	Nine Months Ended September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Service cost	$	34.7		$	29.4		$	—		$	—
Interest cost		26.7			27.8			0.2			0.3
Expected return on assets		(52.8	)		(43.8	)		—			—
Amortization of:
Prior service cost (credit)		0.5			0.5			(0.5	)		(0.6	)
Actuarial loss (gain)		9.2			10.9			(0.1	)		(0.1	)
Net periodic benefit cost (credit)	$	18.3		$	24.8		$	(0.4	)	$	(0.4	)

The service cost component of net periodic benefit cost (credit) is included in Cost of revenues – products and services and Selling, general and administrative expenses. All other components are included in Other nonoperating income, net, in the consolidated statements of earnings and comprehensive earnings.

- Definition

The entire disclosure for retirement benefits.

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+ Details

Commitments and Contingencies

9 Months Ended

Sep. 30, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10.	Commitments and Contingencies

Legal and Administrative Proceedings

The Company is engaged in certain legal and administrative proceedings incidental to its normal business activities, including matters relating to environmental protection. The Company considers various factors in assessing the probable outcome of each matter, including but not limited to the nature of existing legal proceedings and claims, the asserted or possible damages, the jurisdiction and venue of the case and whether it is a jury trial, the progress of the case, existing law and precedent, the opinions or views of legal counsel and other advisers, the Company’s experience in similar cases and the experience of other companies, the facts available to the Company at the time of assessment, and how the Company intends to respond to the proceeding or claim. The Company’s assessment of these factors may change over time as proceedings or claims progress. The Company believes the probability is remote that the outcome of any currently pending legal or administrative proceeding will result in a material loss to the Company as a whole, based on currently available facts.

Borrowing Arrangements with Affiliate

The Company is a co-borrower with an unconsolidated affiliate for a $12.5 million revolving line of credit agreement with Truist Bank, of which $5.4 million was outstanding as of September 30, 2021 and has a maturity date of March 2022. The affiliate has agreed to reimburse and indemnify the Company for any payments and expenses the Company may incur from this agreement. The Company holds a lien on the affiliate’s membership interest in a joint venture as collateral for payment under the revolving line of credit.

In addition, the Company has a $6.0 million interest-only loan, due December 31, 2022, outstanding from this unconsolidated affiliate as of September 30, 2021 and December 31, 2020. The interest rate is one-month LIBOR plus a current spread of 1.75%.

Letters of Credit

In the normal course of business, the Company provides certain third parties with standby letter of credit agreements guaranteeing its payment for certain insurance claims, contract performance and permit requirements. At September 30, 2021, the Company was contingently liable for $35.0 million in letters of credit, of which $2.6 million were issued under the Company’s Revolving Facility.

Business Segments

9 Months Ended

Sep. 30, 2021

Segment Reporting [Abstract]

Business Segments

11.	Business Segments

The Building Materials business contains two reportable segments: the East Group and the West Group. The Company also has a Magnesia Specialties segment. The Company’s evaluation of performance and allocation of resources are based primarily on earnings from operations. Consolidated earnings from operations include total revenues less cost of revenues; selling, general and administrative expenses; acquisition-related expenses; other operating income and expenses, net; and exclude interest expense; other nonoperating income and expenses, net; and income taxes. Corporate loss from operations primarily includes depreciation; expenses for corporate administrative functions; acquisition-related expenses; and other nonrecurring income and expenses excluded from the Company’s evaluation of business segment performance and resource allocation. All long-term debt and related interest expense are held at Corporate.

The following table displays selected financial data for the Company’s reportable segments. Total revenues, as presented on the consolidated statements of earnings and comprehensive earnings, exclude intersegment revenues, which represent sales from one segment to another segment and are eliminated in consolidation.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Total revenues:
East Group	$	684.1		$	549.3		$	1,714.4		$	1,465.9
West Group		794.8			711.2			1,978.2			1,904.2
Total Building Materials business		1,478.9			1,260.5			3,692.6			3,370.1
Magnesia Specialties		78.4			60.9			225.0			180.2
Total	$	1,557.3		$	1,321.4		$	3,917.6		$	3,550.3

Products and services revenues:
East Group	$	641.8		$	514.1		$	1,610.9		$	1,371.8
West Group		749.0			671.4			1,861.9			1,785.4
Total Building Materials business		1,390.8			1,185.5			3,472.8			3,157.2
Magnesia Specialties		71.9			55.2			207.1			164.0
Total	$	1,462.7		$	1,240.7		$	3,679.9		$	3,321.2

Earnings (Loss) from operations:
East Group	$	205.8		$	181.4		$	465.3		$	386.1
West Group		150.6			212.3			284.2			368.2
Total Building Materials business		356.4			393.7			749.5			754.3
Magnesia Specialties		23.1			16.4			69.8			51.2
Corporate		(22.6	)		(9.5	)		(55.6	)		(40.7	)
Total	$	356.9		$	400.6		$	763.7		$	764.8

	September 30, 2021		December 31, 2020
Assets employed:	(Dollars in Millions)
East Group	$	5,075.9	$	4,342.5
West Group		5,613.4		5,355.5
Total Building Materials business		10,689.3		9,698.0
Magnesia Specialties		169.6		167.9
Corporate		2,927.3		714.9
Total	$	13,786.2	$	10,580.8

The increase in assets from December 31, 2020 to September 30, 2021 primarily relates to the proceeds from the Senior Notes issued in July 2021, new right-of-use assets for finance leases and the Tiller and SCC acquisitions. The proceeds from the Senior Notes issuance are reflected as Corporate assets as of September 30, 2021.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Revenues and Gross Profit

9 Months Ended

Sep. 30, 2021

Revenues And Gross Profit [Abstract]

Revenues and Gross Profit

12.	Revenues and Gross Profit

The Building Materials business includes the aggregates, cement, ready mixed concrete and asphalt and paving product lines. Cement and ready mixed concrete product lines and paving services reside only in the West Group. The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Total revenues:
Building Materials business:
Products and services:
Aggregates	$	857.1		$	766.9		$	2,231.5		$	2,092.1
Cement		132.3			115.6			358.4			331.7
Ready mixed concrete		320.8			254.6			824.5			689.4
Asphalt and paving services		195.9			129.8			343.5			254.9
Less: interproduct revenues		(115.3	)		(81.4	)		(285.1	)		(210.9	)
Products and services		1,390.8			1,185.5			3,472.8			3,157.2
Freight		88.1			75.0			219.8			212.9
Total Building Materials business		1,478.9			1,260.5			3,692.6			3,370.1
Magnesia Specialties:
Products and services		71.9			55.2			207.1			164.0
Freight		6.5			5.7			17.9			16.2
Total Magnesia Specialties		78.4			60.9			225.0			180.2
Total	$	1,557.3		$	1,321.4		$	3,917.6		$	3,550.3

Gross profit (loss):
Building Materials business:
Products and services:
Aggregates	$	292.9		$	279.1		$	687.7		$	640.4
Cement		49.9			46.5			101.3			117.2
Ready mixed concrete		31.4			24.7			69.9			56.7
Asphalt and paving services		38.9			32.6			59.4			46.4
Products and services		413.1			382.9			918.3			860.7
Freight		1.3			0.9			1.7			0.3
Total Building Materials business		414.4			383.8			920.0			861.0
Magnesia Specialties:
Products and services		28.1			21.0			84.4			65.3
Freight		(1.1	)		(1.0	)		(3.0	)		(3.2	)
Total Magnesia Specialties		27.0			20.0			81.4			62.1
Corporate		0.5			0.7			0.3			4.3
Total	$	441.9		$	404.5		$	1,001.7		$	927.4

Supplemental Cash Flow Information

9 Months Ended

Sep. 30, 2021

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

13.	Supplemental Cash Flow Information

Noncash investing and financing activities are as follows:

	Nine Months Ended
	September 30,
	2021			2020
	(Dollars in Millions)
Noncash investing and financing activities:
Right-of-use assets obtained in exchange for new finance lease liabilities	$	177.8		$	15.0
Right-of-use assets obtained in exchange for new operating lease liabilities	$	17.3		$	29.3
Accrued liabilities for purchases of property, plant and equipment	$	28.6		$	30.5
Remeasurement of operating lease right-of-use assets	$	(12.4	)	$	1.9

For the nine months ended September 30, 2021, the right-of-use assets obtained in exchange for new finance lease liabilities balance was primarily attributable to the leases of the new corporate headquarters, production equipment and leases assumed as part acquisitions completed during the year.

Supplemental disclosures of cash flow information are as follows:

	Nine Months Ended
	September 30,
	2021		2020
	(Dollars in Millions)
Cash paid for interest, net of capitalized amount	$	68.7	$	74.7
Cash paid for income taxes, net of refunds	$	101.1	$	68.9

During the nine months ended September 30, 2021 and 2020, the Company received proceeds of $13.9 million and repaid $13.7 million of loans, respectively, related to its company-owned life insurance policies. The proceeds and repayment, as applicable, are included in the Investments in life insurance contracts, net, in the investing activities of the consolidated statements of cash flows.

Other Operating Income, Net

9 Months Ended

Sep. 30, 2021

Other Income And Expenses [Abstract]

Other Operating Income, Net

14.	Other Operating Income, Net

Other operating income, net, for the nine months ended September 30, 2021 included a gain on the sale of the Company’s former corporate headquarters of $12.3 million. Other operating income, net for the three and nine months ended September 30, 2020 included $69.9 million on nonrecurring gains on the sales of investment land and divested assets, which are recorded in the West Group.

Other Nonoperating Income, Net

9 Months Ended

Sep. 30, 2021

Other Income And Expenses [Abstract]

Other Nonoperating Income, Net

15.	Other Nonoperating Income, Net

For the three and nine months ended September 30, 2021, the increase in other nonoperating income, net, was primarily attributable to lower pension expense of $3.9 million and $11.8 million, respectively, compared with the prior-year periods. For the nine months ended September 30, 2020, other nonoperating income, net, included $5.6 million of third-party railroad track maintenance expense and reflected a $8.9 million reduction in pension expense compared with the prior-year period.

Subsequent Event

9 Months Ended

Sep. 30, 2021

Subsequent Events [Abstract]

Subsequent Event

16.	Subsequent Event

On October 1, 2021, the Company successfully completed its previously announced acquisition of the Lehigh West Region business for $2.3 billion in cash. The acquisition was primarily financed using proceeds from the issuance of publicly traded debt during the quarter ended September 30, 2021.

Lehigh West Region has a portfolio of 17 active aggregates quarries, two cement plants (with related distribution terminals), and targeted downstream operations in four states. These operations provide a new upstream, materials-led growth platform across several of the nation’s largest and fastest growing megaregions in California and Arizona, solidifying the Company’s position as a leading coast-to-coast aggregates producer.

The acquisition reflects a stock transaction where the Company acquired 100% of the voting interest of the legal entities that comprise the Lehigh West Region. For tax purposes, the acquisition is being treated as an asset transaction. The Company acquired inventories; property, plant and equipment; intangible assets; right-of-use assets; and other assets; and assumed accrued liabilities, asset retirement obligations, lease obligations and other liabilities. The Company did not acquire any of Lehigh West Region’s cash, cash equivalents or accounts receivable nor did it assume any accounts payable, outstanding debt, or pension obligation. The Company is in the process of determining the acquisition-date fair values of assets acquired and liabilities assumed, and as of November 2, 2021, the initial accounting for the business combination has not been completed.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2021

Accounting Policies [Abstract]

Organization

The Company’s Building Materials business includes two reportable segments: the East Group and the West Group.

BUILDING MATERIALS BUSINESS
Reportable Segments	East Group	West Group
Operating Locations	Alabama, Florida, Georgia, Indiana, Iowa, Kansas, Kentucky, Maryland, Minnesota, Missouri, eastern Nebraska, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, Nova Scotia and The Bahamas	Arkansas, Colorado, Louisiana, western Nebraska, Oklahoma, Texas, Utah, Washington and Wyoming

Product Lines	Aggregates and Asphalt	Aggregates, Cement, Ready Mixed Concrete, Asphalt and Paving

Basis of Presentation

consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

Reclassifications

Consolidated Comprehensive Earnings and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(Dollars in Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Other comprehensive earnings, net of tax		1.6		3.6		7.0		7.2
Comprehensive earnings attributable to Martin Marietta	$	256.2	$	298.0	$	552.7	$	545.2

Changes in accumulated other comprehensive loss, net of tax, are as follows:

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Three Months Ended September 30, 2021
Balance at beginning of period	$	(153.5	)	$	0.5		$	(153.0	)
Other comprehensive loss before reclassifications, net of tax		—			(0.6	)		(0.6	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.2			—			2.2
Other comprehensive earnings (loss), net of tax		2.2			(0.6	)		1.6
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Three Months Ended September 30, 2020
Balance at beginning of period	$	(140.0	)	$	(2.2	)	$	(142.2	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		3.1			—			3.1
Other comprehensive earnings, net of tax		3.1			0.5			3.6
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Nine Months Ended September 30, 2021
Balance at beginning of period	$	(158.1	)	$	(0.3	)	$	(158.4	)
Other comprehensive earnings before reclassifications, net of tax		—			0.2			0.2
Amounts reclassified from accumulated other comprehensive loss, net of tax		6.8			—			6.8
Other comprehensive earnings, net of tax		6.8			0.2			7.0
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Nine Months Ended September 30, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(0.8	)		(0.8	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		8.0			—			8.0
Other comprehensive earnings (loss), net of tax		8.0			(0.8	)		7.2
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

Changes in net noncurrent deferred tax assets related to accumulated other comprehensive loss are as follows:

	Pension and Postretirement Benefit Plans
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Balance at beginning of period	$	87.9		$	83.6		$	89.4		$	85.2
Tax effect of other comprehensive earnings		(0.8	)		(1.1	)		(2.3	)		(2.7	)
Balance at end of period	$	87.1		$	82.5		$	87.1		$	82.5

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Nine Months Ended						Affected line items in the
	September 30,						September 30,						consolidated statements of earnings
	2021			2020			2021			2020			and comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	—		$	—		$	(0.1	)
Actuarial loss		3.0			4.2			9.1			10.8		Other nonoperating income, net
		3.0			4.2			9.1			10.7
Tax benefit		(0.8	)		(1.1	)		(2.3	)		(2.7	)	Income tax expense
	$	2.2		$	3.1		$	6.8		$	8.0

Earnings per Common Share

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(In Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.3		—		0.5
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta	$	254.6	$	294.1	$	545.7	$	537.5

Basic weighted-average common shares outstanding		62.4		62.3		62.4		62.3
Effect of dilutive employee and director awards		0.2		0.1		0.2		0.1
Diluted weighted-average common shares outstanding		62.6		62.4		62.6		62.4

Restricted Cash

	September 30,		December 31,
	2021		2020
	(Dollars in Millions)
Cash and cash equivalents	$	2,381.4	$	207.3
Restricted cash		1.7		97.1
Total cash, cash equivalents and restricted cash presented in the consolidated statements of cash flows	$	2,383.1	$	304.4

New Accounting Pronouncement

Policy Elections

Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2021

Significant Accounting Policies [Line Items]

Changes in Accumulated Other Comprehensive Loss Net of Tax

Changes in accumulated other comprehensive loss, net of tax, are as follows:

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Three Months Ended September 30, 2021
Balance at beginning of period	$	(153.5	)	$	0.5		$	(153.0	)
Other comprehensive loss before reclassifications, net of tax		—			(0.6	)		(0.6	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.2			—			2.2
Other comprehensive earnings (loss), net of tax		2.2			(0.6	)		1.6
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Three Months Ended September 30, 2020
Balance at beginning of period	$	(140.0	)	$	(2.2	)	$	(142.2	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		3.1			—			3.1
Other comprehensive earnings, net of tax		3.1			0.5			3.6
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans			Foreign Currency			Accumulated Other Comprehensive Loss
	Nine Months Ended September 30, 2021
Balance at beginning of period	$	(158.1	)	$	(0.3	)	$	(158.4	)
Other comprehensive earnings before reclassifications, net of tax		—			0.2			0.2
Amounts reclassified from accumulated other comprehensive loss, net of tax		6.8			—			6.8
Other comprehensive earnings, net of tax		6.8			0.2			7.0
Balance at end of period	$	(151.3	)	$	(0.1	)	$	(151.4	)

	Nine Months Ended September 30, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(0.8	)		(0.8	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		8.0			—			8.0
Other comprehensive earnings (loss), net of tax		8.0			(0.8	)		7.2
Balance at end of period	$	(136.9	)	$	(1.7	)	$	(138.6	)

Noncurrent Deferred Tax Assets Recorded In Accumulated Other Comprehensive Loss

Changes in net noncurrent deferred tax assets related to accumulated other comprehensive loss are as follows:

	Pension and Postretirement Benefit Plans
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Balance at beginning of period	$	87.9		$	83.6		$	89.4		$	85.2
Tax effect of other comprehensive earnings		(0.8	)		(1.1	)		(2.3	)		(2.7	)
Balance at end of period	$	87.1		$	82.5		$	87.1		$	82.5

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Nine Months Ended						Affected line items in the
	September 30,						September 30,						consolidated statements of earnings
	2021			2020			2021			2020			and comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	—		$	—		$	(0.1	)
Actuarial loss		3.0			4.2			9.1			10.8		Other nonoperating income, net
		3.0			4.2			9.1			10.7
Tax benefit		(0.8	)		(1.1	)		(2.3	)		(2.7	)	Income tax expense
	$	2.2		$	3.1		$	6.8		$	8.0

Basic and Diluted Earnings Per Common Share

The following table reconciles the numerator and denominator for basic and diluted earnings per common share:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(In Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.3		—		0.5
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta	$	254.6	$	294.1	$	545.7	$	537.5

Basic weighted-average common shares outstanding		62.4		62.3		62.4		62.3
Effect of dilutive employee and director awards		0.2		0.1		0.2		0.1
Diluted weighted-average common shares outstanding		62.6		62.4		62.6		62.4

Reconciliation of Cash, Cash Equivalents and Restricted Cash

	September 30,		December 31,
	2021		2020
	(Dollars in Millions)
Cash and cash equivalents	$	2,381.4	$	207.3
Restricted cash		1.7		97.1
Total cash, cash equivalents and restricted cash presented in the consolidated statements of cash flows	$	2,383.1	$	304.4

Parent

Significant Accounting Policies [Line Items]

Comprehensive Earnings

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
	(Dollars in Millions)
Net earnings attributable to Martin Marietta	$	254.6	$	294.4	$	545.7	$	538.0
Other comprehensive earnings, net of tax		1.6		3.6		7.0		7.2
Comprehensive earnings attributable to Martin Marietta	$	256.2	$	298.0	$	552.7	$	545.2

Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2021

Revenue From Contract With Customer [Abstract]

Schedule of Company's Total Revenues by Category for each Reportable Segment

The following table presents the Company’s total revenues by category for each reportable segment.

	Three Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	641.8	$	42.3	$	684.1
West Group		749.0		45.8		794.8
Total Building Materials business		1,390.8		88.1		1,478.9
Magnesia Specialties		71.9		6.5		78.4
Total	$	1,462.7	$	94.6	$	1,557.3

	Three Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	514.1	$	35.2	$	549.3
West Group		671.4		39.8		711.2
Total Building Materials business		1,185.5		75.0		1,260.5
Magnesia Specialties		55.2		5.7		60.9
Total	$	1,240.7	$	80.7	$	1,321.4

	Nine Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,610.9	$	103.5	$	1,714.4
West Group		1,861.9		116.3		1,978.2
Total Building Materials business		3,472.8		219.8		3,692.6
Magnesia Specialties		207.1		17.9		225.0
Total	$	3,679.9	$	237.7	$	3,917.6

	Nine Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,371.8	$	94.1	$	1,465.9
West Group		1,785.4		118.8		1,904.2
Total Building Materials business		3,157.2		212.9		3,370.1
Magnesia Specialties		164.0		16.2		180.2
Total	$	3,321.2	$	229.1	$	3,550.3

Summary of Information About the Company's Contract Balances

The following table presents information about the Company’s contract balances:

(Dollars in Millions)	September 30, 2021		December 31, 2020
Costs in excess of billings	$	10.8	$	2.2
Billings in excess of costs	$	10.7	$	14.0

Goodwill and Other Intangibles (Tables)

9 Months Ended

Sep. 30, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Changes in Goodwill

The following table shows the changes in goodwill by reportable segment and in total:

	East		West
	Group		Group			Total
	(Dollars in Millions)
Balance at January 1, 2021	$	572.5	$	1,841.5		$	2,414.0
Acquisitions		185.9		12.8			198.7
Goodwill allocated to assets held for sale		—		(2.1	)		(2.1	)
Balance at September 30, 2021	$	758.4	$	1,852.2		$	2,610.6

Intangible Assets Subject to Amortization

Intangible assets subject to amortization consist of the following:

	Gross Amount		Accumulated Amortization			Net Balance
(Dollars in Millions)	September 30, 2021
Noncompetition agreements	$	4.2	$	(4.1	)	$	0.1
Customer relationships		312.7		(44.3	)		268.4
Operating permits		523.8		(53.7	)		470.1
Use rights and other		16.4		(13.8	)		2.6
Trade names		23.3		(13.3	)		10.0
Total	$	880.4	$	(129.2	)	$	751.2

	December 31, 2020
Noncompetition agreements	$	4.2	$	(4.1	)	$	0.1
Customer relationships		91.3		(35.6	)		55.7
Operating permits		460.8		(48.4	)		412.4
Use rights and other		16.3		(13.0	)		3.3
Trade names		12.8		(12.3	)		0.5
Total	$	585.4	$	(113.4	)	$	472.0

Intangible Assets Deemed to Indefinite Life and Not Being Amortized

At September 30, 2021 and December 31, 2020, intangible assets deemed to have an indefinite life and not being amortized consist of the following:

(Dollars in Millions)	Building Materials business		Magnesia Specialties		Total
Operating permits	$	6.6	$	—	$	6.6
Use rights		26.7		—		26.7
Trade names		0.2		2.5		2.7
Total	$	33.5	$	2.5	$	36.0

Summary of Intangible Assets Acquired

For the nine months ended September 30, 2021, the Company acquired $294.9 million of intangibles, which consists of the following:

(Dollars in Millions)	Amount		Weighted-average amortization period
Subject to amortization:
Customer relationships	$	221.4	24 years
Permits		63.0	40 years
Trade name		10.5	9 years
Total	$	294.9	27 years

Estimated Amortization Expense of Intangibles

The estimated amortization expense for intangibles for the remainder of 2021, each of the next four years, and thereafter is as follows:

(Dollars in Millions)
October - December 2021	$	6.4
2022		25.0
2023		24.7
2024		24.4
2025		24.3
Thereafter		646.4
Total	$	751.2

Inventories, Net (Tables)

9 Months Ended

Sep. 30, 2021

Inventory Disclosure [Abstract]

Schedule of Inventories Net

	September 30,			December 31,
	2021			2020
	(Dollars in Millions)
Finished products	$	683.2		$	667.0
Products in process		25.6			37.1
Raw materials		55.9			35.3
Supplies and expendable parts		152.0			149.9
		916.7			889.3
Less: Allowances		(199.2	)		(180.3	)
Total	$	717.5		$	709.0

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2021

Debt Disclosure [Abstract]

Long-Term Debt

	September 30,			December 31,
	2021			2020
	(Dollars in Millions)
0.650% Senior Notes, due 2023	$	696.9		$	—
4.250% Senior Notes, due 2024		398.1			397.6
7% Debentures, due 2025		124.5			124.5
3.450% Senior Notes, due 2027		297.9			297.6
3.500% Senior Notes, due 2027		496.2			495.8
2.500% Senior Notes, due 2030		490.9			490.1
2.400% Senior Notes, due 2031		891.7			—
6.25% Senior Notes, due 2037		228.3			228.2
4.250% Senior Notes, due 2047		592.0			591.9
3.200% Senior Notes, due 2051		882.9			—
Trade Receivable Facility, interest rate of 0.77 % at September 30, 2021		20.0			—
Other notes		0.1			0.1
Total debt		5,119.5			2,625.8
Less: Current maturities of long-term debt		(20.1	)		—
Long-term debt	$	5,099.4		$	2,625.8

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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-Topic 235
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-URI http://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

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+ Details

Pension and Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2021

Compensation And Retirement Disclosure [Abstract]

Schedule of Components of Net Periodic Benefit Cost (Credit)

The estimated components of the recorded net periodic benefit cost (credit) for pension and postretirement benefits are as follows:

	Pension						Postretirement Benefits
	Three Months Ended September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Service cost	$	11.6		$	9.8		$	—		$	—
Interest cost		8.9			9.3			0.1			0.1
Expected return on assets		(17.7	)		(15.2	)		—			—
Amortization of:
Prior service cost (credit)		0.2			0.2			(0.2	)		(0.2	)
Actuarial loss		3.0			4.2			—			—
Net periodic benefit cost (credit)	$	6.0		$	8.3		$	(0.1	)	$	(0.1	)

	Pension						Postretirement Benefits
	Nine Months Ended September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Service cost	$	34.7		$	29.4		$	—		$	—
Interest cost		26.7			27.8			0.2			0.3
Expected return on assets		(52.8	)		(43.8	)		—			—
Amortization of:
Prior service cost (credit)		0.5			0.5			(0.5	)		(0.6	)
Actuarial loss (gain)		9.2			10.9			(0.1	)		(0.1	)
Net periodic benefit cost (credit)	$	18.3		$	24.8		$	(0.4	)	$	(0.4	)

Business Segments (Tables)

9 Months Ended

Sep. 30, 2021

Segment Reporting [Abstract]

Financial Data for Continuing Operation for Company's Reportable Business Segments

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Total revenues:
East Group	$	684.1		$	549.3		$	1,714.4		$	1,465.9
West Group		794.8			711.2			1,978.2			1,904.2
Total Building Materials business		1,478.9			1,260.5			3,692.6			3,370.1
Magnesia Specialties		78.4			60.9			225.0			180.2
Total	$	1,557.3		$	1,321.4		$	3,917.6		$	3,550.3

Products and services revenues:
East Group	$	641.8		$	514.1		$	1,610.9		$	1,371.8
West Group		749.0			671.4			1,861.9			1,785.4
Total Building Materials business		1,390.8			1,185.5			3,472.8			3,157.2
Magnesia Specialties		71.9			55.2			207.1			164.0
Total	$	1,462.7		$	1,240.7		$	3,679.9		$	3,321.2

Earnings (Loss) from operations:
East Group	$	205.8		$	181.4		$	465.3		$	386.1
West Group		150.6			212.3			284.2			368.2
Total Building Materials business		356.4			393.7			749.5			754.3
Magnesia Specialties		23.1			16.4			69.8			51.2
Corporate		(22.6	)		(9.5	)		(55.6	)		(40.7	)
Total	$	356.9		$	400.6		$	763.7		$	764.8

	September 30, 2021		December 31, 2020
Assets employed:	(Dollars in Millions)
East Group	$	5,075.9	$	4,342.5
West Group		5,613.4		5,355.5
Total Building Materials business		10,689.3		9,698.0
Magnesia Specialties		169.6		167.9
Corporate		2,927.3		714.9
Total	$	13,786.2	$	10,580.8

Revenues and Gross Profit (Tables)

9 Months Ended

Sep. 30, 2021

Revenues And Gross Profit [Abstract]

Total Revenues and Gross Profit by Product Line

The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2021			2020			2021			2020
	(Dollars in Millions)
Total revenues:
Building Materials business:
Products and services:
Aggregates	$	857.1		$	766.9		$	2,231.5		$	2,092.1
Cement		132.3			115.6			358.4			331.7
Ready mixed concrete		320.8			254.6			824.5			689.4
Asphalt and paving services		195.9			129.8			343.5			254.9
Less: interproduct revenues		(115.3	)		(81.4	)		(285.1	)		(210.9	)
Products and services		1,390.8			1,185.5			3,472.8			3,157.2
Freight		88.1			75.0			219.8			212.9
Total Building Materials business		1,478.9			1,260.5			3,692.6			3,370.1
Magnesia Specialties:
Products and services		71.9			55.2			207.1			164.0
Freight		6.5			5.7			17.9			16.2
Total Magnesia Specialties		78.4			60.9			225.0			180.2
Total	$	1,557.3		$	1,321.4		$	3,917.6		$	3,550.3

Gross profit (loss):
Building Materials business:
Products and services:
Aggregates	$	292.9		$	279.1		$	687.7		$	640.4
Cement		49.9			46.5			101.3			117.2
Ready mixed concrete		31.4			24.7			69.9			56.7
Asphalt and paving services		38.9			32.6			59.4			46.4
Products and services		413.1			382.9			918.3			860.7
Freight		1.3			0.9			1.7			0.3
Total Building Materials business		414.4			383.8			920.0			861.0
Magnesia Specialties:
Products and services		28.1			21.0			84.4			65.3
Freight		(1.1	)		(1.0	)		(3.0	)		(3.2	)
Total Magnesia Specialties		27.0			20.0			81.4			62.1
Corporate		0.5			0.7			0.3			4.3
Total	$	441.9		$	404.5		$	1,001.7		$	927.4

Supplemental Cash Flow Information (Tables)

9 Months Ended

Sep. 30, 2021

Supplemental Cash Flow Elements [Abstract]

Schedule of Noncash Investing and Financing Activities

Noncash investing and financing activities are as follows:

	Nine Months Ended
	September 30,
	2021			2020
	(Dollars in Millions)
Noncash investing and financing activities:
Right-of-use assets obtained in exchange for new finance lease liabilities	$	177.8		$	15.0
Right-of-use assets obtained in exchange for new operating lease liabilities	$	17.3		$	29.3
Accrued liabilities for purchases of property, plant and equipment	$	28.6		$	30.5
Remeasurement of operating lease right-of-use assets	$	(12.4	)	$	1.9

Supplemental Disclosures of Cash Flow Information

Supplemental disclosures of cash flow information are as follows:

	Nine Months Ended
	September 30,
	2021		2020
	(Dollars in Millions)
Cash paid for interest, net of capitalized amount	$	68.7	$	74.7
Cash paid for income taxes, net of refunds	$	101.1	$	68.9

Significant Accounting Policies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) Facility State Segment	Dec. 31, 2020 USD ($)
Accounting Policies [Abstract]
Number of quarries and yards \| Facility	320
Number of states with aggregates business sales by destination \| State	26
Reportable business segments \| Segment	2
Restricted cash \| $	$ 1.7	$ 97.1

Significant Accounting Policies - Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta	$ 254.6	$ 294.4	$ 545.7	$ 538.0
Other comprehensive earnings, net of tax	1.6	3.6	7.0	7.2
Earnings attributable to Martin Marietta Materials, Inc.	$ 256.2	$ 298.0	$ 552.7	$ 545.2

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Significant Accounting Policies - Changes in Accumulated Other Comprehensive Loss Net of Tax (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 6,128.2	$ 5,493.6	$ 5,893.3	$ 5,353.3
Other comprehensive earnings (loss), net of tax	1.6	3.6	7.0	7.2
Ending Balance	6,358.2	5,758.9	6,358.2	5,758.9
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(153.5)	(140.0)	(158.1)	(144.9)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2.2	3.1	6.8	8.0
Other comprehensive earnings (loss), net of tax	2.2	3.1	6.8	8.0
Ending Balance	(151.3)	(136.9)	(151.3)	(136.9)
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	0.5	(2.2)	(0.3)	(0.9)
Other comprehensive earnings (loss) before reclassifications, net of tax	(0.6)	0.5	0.2	(0.8)
Other comprehensive earnings (loss), net of tax	(0.6)	0.5	0.2	(0.8)
Ending Balance	(0.1)	(1.7)	(0.1)	(1.7)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(153.0)	(142.2)	(158.4)	(145.8)
Other comprehensive earnings (loss) before reclassifications, net of tax	(0.6)	0.5	0.2	(0.8)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2.2	3.1	6.8	8.0
Other comprehensive earnings (loss), net of tax	1.6	3.6	7.0	7.2
Ending Balance	$ (151.4)	$ (138.6)	$ (151.4)	$ (138.6)

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 848
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Publisher FASB
-Subparagraph (a)(3)(iii)(03)

+ Details

Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 87.9	$ 83.6	$ 89.4	$ 85.2
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(0.8)	(1.1)	(2.3)	(2.7)
Balance at end of period, Pension and Postretirement Benefit Plans	$ 87.1	$ 82.5	$ 87.1	$ 82.5

Significant Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit	$ 63.6	$ 81.5	$ 141.7	$ 143.0
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	2.2	3.1	6.8	8.0
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit				(0.1)
Total reclassifications out of accumulated other comprehensive loss before taxes	3.0	4.2	9.1	10.7
Tax benefit	(0.8)	(1.1)	(2.3)	(2.7)
Earnings from Continuing Operations	2.2	3.1	6.8	8.0
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans \| Other Nonoperating Income, Net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial loss	$ 3.0	$ 4.2	$ 9.1	$ 10.8

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Significant Accounting Policies - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta	$ 254.6	$ 294.4	$ 545.7	$ 538.0
Less: Distributed and undistributed earnings attributable to unvested awards		0.3		0.5
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta	$ 254.6	$ 294.1	$ 545.7	$ 537.5
Basic weighted-average common shares outstanding	62.4	62.3	62.4	62.3
Effect of dilutive employee and director awards	0.2	0.1	0.2	0.1
Diluted weighted-average common shares outstanding	62.6	62.4	62.6	62.4

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Restricted Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 2,381.4	$ 207.3
Restricted cash	1.7	97.1
Total cash, cash equivalents and restricted cash presented in the consolidated statements of cash flows	$ 2,383.1	$ 304.4

Revenue Recognition - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue Recognition [Line Items]
Performance obligations, description of timing			Performance obligations within paving service agreements are satisfied over time, primarily ranging from one day to two years. For product revenues and freight revenues, customer payment terms are generally 30 days from invoice date. Customer payments for the paving operations are based on a contractual billing schedule and are due 30 days from invoice date.
Product and freight revenues customer payment terms			30 days
Customer payments terms based on contractual billing			30 days
Future revenues from unsatisfied performance obligations	$ 183.0	$ 150.2	$ 183.0	$ 150.2
Service revenues	1,557.3	1,321.4	3,917.6	3,550.3
Revenue recognized from contract liabilities	7.1	8.5	11.9	7.2
Retainage on contracts	10.0		10.0		$ 10.6
Service \| COLORADO
Revenue Recognition [Line Items]
Service revenues			$ 182.7	$ 221.3
Service \| COLORADO \| West Group
Revenue Recognition [Line Items]
Service revenues	$ 100.5	$ 112.8
Minimum \| Service
Revenue Recognition [Line Items]
Performance obligations, period			1 day
Maximum \| Service
Revenue Recognition [Line Items]
Performance obligations, period			2 years

Revenue Recognition - Additional Information (Detail 1)	Sep. 30, 2021	Sep. 30, 2020
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-10-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		1 month
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-10-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	1 month
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-10-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		13 months
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-10-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	21 months

Revenue Recognition - Schedule of Company's Total Revenues by Category for each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue Recognition [Line Items]
Total	$ 1,557.3	$ 1,321.4	$ 3,917.6	$ 3,550.3
Building Materials Business
Revenue Recognition [Line Items]
Total	1,478.9	1,260.5	3,692.6	3,370.1
Products and Services
Revenue Recognition [Line Items]
Total	1,462.7	1,240.7	3,679.9	3,321.2
Products and Services \| Building Materials Business
Revenue Recognition [Line Items]
Total	1,390.8	1,185.5	3,472.8	3,157.2
Freight
Revenue Recognition [Line Items]
Total	94.6	80.7	237.7	229.1
Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	88.1	75.0	219.8	212.9
Operating Segments \| Building Materials Business East Group
Revenue Recognition [Line Items]
Total	684.1	549.3	1,714.4	1,465.9
Operating Segments \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	794.8	711.2	1,978.2	1,904.2
Operating Segments \| Building Materials Business
Revenue Recognition [Line Items]
Total	1,478.9	1,260.5	3,692.6	3,370.1
Operating Segments \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	78.4	60.9	225.0	180.2
Operating Segments \| Products and Services \| Building Materials Business East Group
Revenue Recognition [Line Items]
Total	641.8	514.1	1,610.9	1,371.8
Operating Segments \| Products and Services \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	749.0	671.4	1,861.9	1,785.4
Operating Segments \| Products and Services \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	71.9	55.2	207.1	164.0
Operating Segments \| Freight \| Building Materials Business East Group
Revenue Recognition [Line Items]
Total	42.3	35.2	103.5	94.1
Operating Segments \| Freight \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	45.8	39.8	116.3	118.8
Operating Segments \| Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	88.1	75.0	219.8	212.9
Operating Segments \| Freight \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 6.5	$ 5.7	$ 17.9	$ 16.2

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 32
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 22
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
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-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Revenue Recognition - Summary of Information About the Company's Contract Balances (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Costs in excess of billings	$ 10.8	$ 2.2
Billings in excess of costs	$ 10.7	$ 14.0

Business Combinations - Additional Information (Detail)	Jul. 30, 2021	Apr. 30, 2021
Southern Crushed Concrete
Business Acquisition [Line Items]
Acquisition date	Jul. 30, 2021
Tiller Corporation
Business Acquisition [Line Items]
Acquisition date		Apr. 30, 2021

Goodwill and Other Intangibles - Changes in Goodwill (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Line Items]
Balance at January 1, 2021	$ 2,414.0
Acquisitions	198.7
Goodwill allocated to assets held for sale	(2.1)
Balance at September 30, 2021	2,610.6
East Group
Goodwill [Line Items]
Balance at January 1, 2021	572.5
Acquisitions	185.9
Balance at September 30, 2021	758.4
West Group
Goodwill [Line Items]
Balance at January 1, 2021	1,841.5
Acquisitions	12.8
Goodwill allocated to assets held for sale	(2.1)
Balance at September 30, 2021	$ 1,852.2

Goodwill and Other Intangibles - Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 880.4	$ 585.4
Accumulated Amortization	(129.2)	(113.4)
Net Balance	751.2	472.0
Noncompetition agreements
Finite-Lived Intangible Assets [Line Items]
Gross Amount	4.2	4.2
Accumulated Amortization	(4.1)	(4.1)
Net Balance	0.1	0.1
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	312.7	91.3
Accumulated Amortization	(44.3)	(35.6)
Net Balance	268.4	55.7
Operating Permits
Finite-Lived Intangible Assets [Line Items]
Gross Amount	523.8	460.8
Accumulated Amortization	(53.7)	(48.4)
Net Balance	470.1	412.4
Use Rights And Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	16.4	16.3
Accumulated Amortization	(13.8)	(13.0)
Net Balance	2.6	3.3
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Amount	23.3	12.8
Accumulated Amortization	(13.3)	(12.3)
Net Balance	$ 10.0	$ 0.5

Goodwill and Other Intangibles - Intangible Assets Deemed to Indefinite Life and Not Being Amortized (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 36.0	$ 36.0
Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	33.5	33.5
Magnesia Specialties
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2.5	2.5
Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6.6	6.6
Operating Permits \| Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6.6	6.6
Use Rights Not Subject To Amortization
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	26.7	26.7
Use Rights Not Subject To Amortization \| Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	26.7	26.7
Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2.7	2.7
Trade names \| Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	0.2	0.2
Trade names \| Magnesia Specialties
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 2.5	$ 2.5

Goodwill and Other Intangibles - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Intangibles assets acquired	$ 294.9
Amortization expense of intangible assets	$ 15.2	$ 9.8

Goodwill and Other Intangibles - Summary of Intangible Assets Acquired (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Acquired Finite And Indefinite Lived Intangible Assets [Line Items]
Total subject to amortization	$ 294.9
Weighted-average amortization period	27 years
Customer Relationships
Acquired Finite And Indefinite Lived Intangible Assets [Line Items]
Total subject to amortization	$ 221.4
Weighted-average amortization period	24 years
Permits
Acquired Finite And Indefinite Lived Intangible Assets [Line Items]
Total subject to amortization	$ 63.0
Weighted-average amortization period	40 years
Trade names
Acquired Finite And Indefinite Lived Intangible Assets [Line Items]
Total subject to amortization	$ 10.5
Weighted-average amortization period	9 years

Goodwill and Other Intangibles - Estimated Amortization Expense of Intangibles (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
October - December 2021	$ 6.4
2022	25.0
2023	24.7
2024	24.4
2025	24.3
Thereafter	646.4
Net Balance	$ 751.2	$ 472.0

Inventories, Net - Schedule of Inventories Net (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished products	$ 683.2	$ 667.0
Products in process	25.6	37.1
Raw materials	55.9	35.3
Supplies and expendable parts	152.0	149.9
Inventories, Gross	916.7	889.3
Less: Allowances	(199.2)	(180.3)
Total	$ 717.5	$ 709.0

Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt	$ 5,119.5	$ 2,625.8
Less: Current maturities of long-term debt	(20.1)
Long-term debt	5,099.4	2,625.8
0.650% Senior Notes, Due 2023
Debt Instrument [Line Items]
Total debt	696.9
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	398.1	397.6
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124.5	124.5
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	297.9	297.6
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	496.2	495.8
2.500% Senior Notes, Due 2030
Debt Instrument [Line Items]
Total debt	490.9	490.1
2.400% Senior Notes, Due 2031
Debt Instrument [Line Items]
Total debt	891.7
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228.3	228.2
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total debt	592.0	591.9
3.200% Senior Notes, Due 2051
Debt Instrument [Line Items]
Total debt	882.9
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	20.0
Other Notes
Debt Instrument [Line Items]
Total debt	$ 0.1	$ 0.1

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail)		9 Months Ended
	Jul. 02, 2021	Sep. 30, 2021
0.650% Senior Notes, Due 2023
Debt Instrument [Line Items]
Maturity year	2023	2023
Interest rate on notes	0.65%	0.65%
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Maturity year		2024
Interest rate on notes		4.25%
7% Debentures, Due 2025
Debt Instrument [Line Items]
Maturity year		2025
Interest rate on notes		7.00%
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year		2027
Interest rate on notes		3.45%
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year		2027
Interest rate on notes		3.50%
2.500% Senior Notes, Due 2030
Debt Instrument [Line Items]
Maturity year		2030
Interest rate on notes		2.50%
2.400% Senior Notes, Due 2031
Debt Instrument [Line Items]
Maturity year	2031	2031
Interest rate on notes	2.40%	2.40%
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Maturity year		2037
Interest rate on notes		6.25%
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Maturity year		2047
Interest rate on notes		4.25%
3.200% Senior Notes, Due 2051
Debt Instrument [Line Items]
Maturity year	2051	2051
Interest rate on notes	3.20%	3.20%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate		0.77%

Long-Term Debt - Additional Information (Detail) - USD ($)				9 Months Ended
	Sep. 22, 2021	Jul. 02, 2021	Dec. 05, 2016	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation				$ 200,000,000
Outstanding letters of credit				$ 35,000,000.0
Revolving Facility
Debt Instrument [Line Items]
Credit facility commitment			$ 700,000,000
Debt instrument maturity period				Dec. 05, 2024
Outstanding borrowing under credit facility				$ 0	$ 0
Senior unsecured revolving facility, maturity period			5 years
Outstanding letters of credit				2,600,000	2,600,000
Minimum
Debt Instrument [Line Items]
Reduction of consolidated debt in the debt ratio calculation				$ 50,000,000
Maximum \| Including Acquisition Bridge Debt
Debt Instrument [Line Items]
Debt covenant				3.50
Maximum \| Excluding Acquisition Bridge Debt
Debt Instrument [Line Items]
Debt covenant				3.75
0.650% Senior Notes, Due 2023
Debt Instrument [Line Items]
Aggregate principal amount of long term debt		$ 700,000,000
Interest rate on notes		0.65%		0.65%
Maturity year		2023		2023
0.650% Senior Notes, Due 2023 \| Prior to July 2, 2022 (2023 Par Call Date)
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
0.650% Senior Notes, Due 2023 \| Prior to July 2, 2022 (2023 Par Call Date) \| Treasury Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.10%
0.650% Senior Notes, Due 2023 \| On or After 2023 Par Call Date and Prior to Maturity
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
2.400% Senior Notes, Due 2031
Debt Instrument [Line Items]
Aggregate principal amount of long term debt		$ 900,000,000
Interest rate on notes		2.40%		2.40%
Maturity year		2031		2031
2.400% Senior Notes, Due 2031 \| Prior to April 15, 2031 (2031 Par Call Date)
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
2.400% Senior Notes, Due 2031 \| Prior to April 15, 2031 (2031 Par Call Date) \| Treasury Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.15%
2.400% Senior Notes, Due 2031 \| On or After 2031 Par Call Date and Prior to Maturity
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
3.200% Senior Notes, Due 2051
Debt Instrument [Line Items]
Aggregate principal amount of long term debt		$ 900,000,000
Interest rate on notes		3.20%		3.20%
Maturity year		2051		2051
3.200% Senior Notes, Due 2051 \| Prior to January 15, 2051 (2051 Par Call Date)
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
3.200% Senior Notes, Due 2051 \| Prior to January 15, 2051 (2051 Par Call Date) \| Treasury Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.20%
3.200% Senior Notes, Due 2051 \| On or After 2051 Par Call Date and Prior to Maturity
Debt Instrument [Line Items]
Debt instrument redemption price percentage		100.00%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit facility commitment				$ 400,000,000
Debt instrument maturity period	Sep. 21, 2022
Outstanding borrowing under credit facility				20,000,000.0	$ 0
Trade Receivable Facility \| Maximum
Debt Instrument [Line Items]
Line of credit facility, increased borrowing capacity, subject to lender commitments				$ 500,000,000
Trade Receivable Facility \| London Interbank Offered Rate(LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate				0.70%
Trade Receivable Facility \| Conduit Lenders
Debt Instrument [Line Items]
Basis spread on variable rate				0.60%

Financial Instruments - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) Customer	Sep. 30, 2020 Customer	Sep. 30, 2021 USD ($) Customer	Sep. 30, 2020 Customer	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Long-term debt, carrying values	$ 5,119.5		$ 5,119.5		$ 2,625.8
Long-term debt, fair values	$ 5,490.0		$ 5,490.0		$ 3,080.0
Customer Concentration Risk \| Total Revenues
Debt Instrument [Line Items]
Number of customer accounted for 10% or more of consolidated total revenues \| Customer	0	0	0	0
Customer Concentration Risk \| Total Revenues \| Minimum
Debt Instrument [Line Items]
Percentage of concentration risk	10.00%	10.00%	10.00%	10.00%

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References + Details

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Effective change in income tax rate	20.60%	21.00%
Discrete benefit for research and development tax credits	$ 2.9
Discrete benefit from change in tax status of subsidiary from partnership to corporation		$ 6.9

Pension and Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11.6	$ 9.8	$ 34.7	$ 29.4
Interest cost	8.9	9.3	26.7	27.8
Expected return on assets	(17.7)	(15.2)	(52.8)	(43.8)
Prior service cost (credit)	0.2	0.2	0.5	0.5
Actuarial loss (gain)	3.0	4.2	9.2	10.9
Net periodic benefit cost (credit)	6.0	8.3	18.3	24.8
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.1	0.1	0.2	0.3
Prior service cost (credit)	(0.2)	(0.2)	(0.5)	(0.6)
Actuarial loss (gain)			(0.1)	(0.1)
Net periodic benefit cost (credit)	$ (0.1)	$ (0.1)	$ (0.4)	$ (0.4)

Commitments and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Commitments and Contingencies [Line Items]
Guarantee of affiliate's obligations	$ 12,500,000
Due from affiliate	5,400,000
Outstanding letters of credit	35,000,000.0
Revolving Facility
Commitments and Contingencies [Line Items]
Outstanding letters of credit	2,600,000	$ 2,600,000
Interest-only loan
Commitments and Contingencies [Line Items]
Due from affiliate	$ 6,000,000.0	$ 6,000,000.0
Maturity date	Dec. 31, 2022
Interest-only loan \| London Interbank Offered Rate(LIBOR)
Commitments and Contingencies [Line Items]
Basis spread on variable rate	1.75%
Revolving Line Of Credit Expires In August 2015
Commitments and Contingencies [Line Items]
Line of credit maturity period	2022-03

Business Segments - Additional Information (Detail)	9 Months Ended
Business Segments - Additional Information (Detail)	Sep. 30, 2021 Segment
Segment Reporting [Abstract]
Reportable segments	2

Business Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 1,557.3	$ 1,321.4	$ 3,917.6	$ 3,550.3
Earnings (Loss) from operations	356.9	400.6	763.7	764.8
Assets employed	13,786.2		13,786.2		$ 10,580.8
Products and Services
Segment Reporting Information [Line Items]
Total revenues	1,462.7	1,240.7	3,679.9	3,321.2
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	1,478.9	1,260.5	3,692.6	3,370.1
Earnings (Loss) from operations	356.4	393.7	749.5	754.3
Assets employed	10,689.3		10,689.3		9,698.0
Building Materials Business \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	1,390.8	1,185.5	3,472.8	3,157.2
Operating Segments \| Building Materials Business East Group
Segment Reporting Information [Line Items]
Total revenues	684.1	549.3	1,714.4	1,465.9
Earnings (Loss) from operations	205.8	181.4	465.3	386.1
Assets employed	5,075.9		5,075.9		4,342.5
Operating Segments \| Building Materials Business East Group \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	641.8	514.1	1,610.9	1,371.8
Operating Segments \| Building Materials Business West Group
Segment Reporting Information [Line Items]
Total revenues	794.8	711.2	1,978.2	1,904.2
Earnings (Loss) from operations	150.6	212.3	284.2	368.2
Assets employed	5,613.4		5,613.4		5,355.5
Operating Segments \| Building Materials Business West Group \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	749.0	671.4	1,861.9	1,785.4
Operating Segments \| Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues	78.4	60.9	225.0	180.2
Earnings (Loss) from operations	23.1	16.4	69.8	51.2
Assets employed	169.6		169.6		167.9
Operating Segments \| Magnesia Specialties \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	71.9	55.2	207.1	164.0
Operating Segments \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	1,478.9	1,260.5	3,692.6	3,370.1
Corporate
Segment Reporting Information [Line Items]
Earnings (Loss) from operations	(22.6)	$ (9.5)	(55.6)	$ (40.7)
Assets employed	$ 2,927.3		$ 2,927.3		$ 714.9

Revenues and Gross Profit - Total Revenues and Gross Profit by Product Line (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Product Information [Line Items]
Total revenues	$ 1,557.3	$ 1,321.4	$ 3,917.6	$ 3,550.3
Gross profit (loss)	441.9	404.5	1,001.7	927.4
Interproduct Revenues
Product Information [Line Items]
Total revenues	(115.3)	(81.4)	(285.1)	(210.9)
Corporate
Product Information [Line Items]
Gross profit (loss)	0.5	0.7	0.3	4.3
Building Materials Business
Product Information [Line Items]
Total revenues	1,478.9	1,260.5	3,692.6	3,370.1
Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	1,478.9	1,260.5	3,692.6	3,370.1
Gross profit (loss)	414.4	383.8	920.0	861.0
Building Materials Business \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	1,390.8	1,185.5	3,472.8	3,157.2
Gross profit (loss)	413.1	382.9	918.3	860.7
Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	78.4	60.9	225.0	180.2
Gross profit (loss)	27.0	20.0	81.4	62.1
Magnesia Specialties \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	71.9	55.2	207.1	164.0
Gross profit (loss)	28.1	21.0	84.4	65.3
Aggregates \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	857.1	766.9	2,231.5	2,092.1
Gross profit (loss)	292.9	279.1	687.7	640.4
Cement \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	132.3	115.6	358.4	331.7
Gross profit (loss)	49.9	46.5	101.3	117.2
Ready Mixed Concrete \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	320.8	254.6	824.5	689.4
Gross profit (loss)	31.4	24.7	69.9	56.7
Asphalt and Paving \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	195.9	129.8	343.5	254.9
Gross profit (loss)	38.9	32.6	59.4	46.4
Freight
Product Information [Line Items]
Total revenues	94.6	80.7	237.7	229.1
Freight \| Building Materials Business
Product Information [Line Items]
Total revenues	88.1	75.0	219.8	212.9
Freight \| Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	88.1	75.0	219.8	212.9
Gross profit (loss)	1.3	0.9	1.7	0.3
Freight \| Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	6.5	5.7	17.9	16.2
Gross profit (loss)	$ (1.1)	$ (1.0)	$ (3.0)	$ (3.2)

Supplemental Cash Flow Information - Schedule of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 177.8	$ 15.0
Right-of-use assets obtained in exchange for new operating lease liabilities	17.3	29.3
Accrued liabilities for purchases of property, plant and equipment	28.6	30.5
Remeasurement of operating lease right-of-use assets	$ (12.4)	$ 1.9

Supplemental Cash Flow Information - Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest, net of capitalized amount	$ 68.7	$ 74.7
Cash paid for income taxes, net of refunds	$ 101.1	$ 68.9

Supplemental Cash Flow Information - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Repayment of loans related to life insurance policies	$ 13.9	$ 13.7

Other Operating Income, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Component of Other Operating Income and Expense [Line Items]
Gains on sales of investment		$ 26.6	$ 71.2
Former Corporate Headquarters \| Other Operating Income, Net
Component of Other Operating Income and Expense [Line Items]
Gains on sales of investment		$ 12.3
Land and Divested Assets \| Other Operating Income, Net \| West Group
Component of Other Operating Income and Expense [Line Items]
Gains on sales of investment	$ 69.9		$ 69.9

Other Nonoperating Income, Net - Additional Information (Detail) - Other Nonoperating Income, Net - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Component of Other Income And Expense [Line Items]
Reduction in pension expense	$ 3.9	$ 11.8	$ 8.9
Third-party railroad track maintenance expense			$ 5.6

Subsequent Event - Additional Information (Detail) - Subsequent Event - Lehigh West Region $ in Billions	Oct. 01, 2021 USD ($) State Quarry Plant
Subsequent Event [Line Items]
Business combination, effective date	Oct. 01, 2021
Cash transferred in business combination \| $	$ 2.3
Business combination, number of active aggregate quarries acquired \| Quarry	17
Business combination, number of cement plants acquired \| Plant	2
Business combination, number of states targeted for downstream operations \| State	4
Business acquisition, percentage of voting interests acquired	100.00%