View Filing Data

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2020	Apr. 29, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
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	2710 Wycliff Road
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27607-3033
City Area Code	919
Local Phone Number	781-4550
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		62,241,366

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 424.0	$ 21.0
Accounts receivable, net	562.8	573.7
Inventories, net	700.5	690.8
Other current assets	145.7	141.2
Total Current Assets	1,833.0	1,426.7
Property, plant and equipment	8,691.1	8,633.5
Allowances for depreciation, depletion and amortization	(3,505.7)	(3,427.5)
Net property, plant and equipment	5,185.4	5,206.0
Goodwill	2,397.1	2,396.8
Other intangibles, net	483.3	486.8
Operating lease right-of-use assets, net	477.9	481.9
Other noncurrent assets	126.7	133.4
Total Assets	10,503.4	10,131.6
Current Liabilities:
Accounts payable	202.0	229.6
Accrued salaries, benefits and payroll taxes	31.6	56.7
Accrued insurance and other taxes	47.2	63.1
Current maturities of long-term debt and short-term facilities	639.9	340.0
Operating lease liabilities	52.9	52.7
Other current liabilities	102.0	96.4
Total Current Liabilities	1,075.6	838.5
Long-term debt	2,623.9	2,433.6
Deferred income taxes, net	737.0	733.0
Noncurrent operating lease liabilities	429.2	433.9
Other noncurrent liabilities	338.3	339.3
Total Liabilities	5,204.0	4,778.3
Equity:
Common stock, par value $0.01 per share	0.6	0.6
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,423.1	3,418.8
Accumulated other comprehensive loss	(145.4)	(145.8)
Retained earnings	2,018.6	2,077.2
Total Shareholders' Equity	5,296.9	5,350.8
Noncontrolling interests	2.5	2.5
Total Equity	5,299.4	5,353.3
Total Liabilities and Equity	$ 10,503.4	$ 10,131.6

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
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
	Mar. 31, 2020	Mar. 31, 2019
Total Revenues	$ 958.2	$ 939.0
Total Cost of Revenues	815.8	796.1
Gross Profit	142.4	142.9
Selling, general & administrative expenses	78.7	78.3
Acquisition-related expenses	0.3	0.1
Other operating expenses and (income), net	5.6	(4.7)
Earnings from Operations	57.8	69.2
Interest expense	29.8	32.9
Other nonoperating expenses and (income), net	2.0	(1.6)
Earnings before income tax expense (benefit)	26.0	37.9
Income tax expense (benefit)	0.1	(5.0)
Consolidated net earnings	25.9	42.9
Net Earnings Attributable to Martin Marietta Materials, Inc.	25.9	42.9
Consolidated Comprehensive Earnings:
Earnings attributable to Martin Marietta Materials, Inc.	26.3	46.1
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 26.3	$ 46.1
Net Earnings Attributable to Martin Marietta Materials, Inc. Per Common Share:
Basic attributable to common shareholders	$ 0.42	$ 0.68
Diluted attributable to common shareholders	$ 0.41	$ 0.68
Weighted-Average Common Shares Outstanding:
Basic	62.3	62.6
Diluted	62.5	62.8
Products and Services
Total Revenues	$ 891.0	$ 878.3
Total Cost of Revenues	747.4	734.2
Freight
Total Revenues	67.2	60.7
Total Cost of Revenues	$ 68.4	$ 61.9

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows from Operating Activities:
Consolidated net earnings	$ 25.9	$ 42.9
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	95.0	89.2
Stock-based compensation expense	12.5	13.5
Gain on divestitures and sales of assets	(1.5)	(2.4)
Deferred income taxes	3.2	4.8
Other items, net	(0.4)	0.5
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	10.2	(26.1)
Inventories, net	(9.6)	16.4
Accounts payable	4.9	20.4
Other assets and liabilities, net	(33.5)	(41.3)
Net Cash Provided by Operating Activities	106.7	117.9
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(104.1)	(130.1)
Proceeds from divestitures and sales of assets	15.9	3.0
Investments in life insurance contracts, net	(7.2)	0.2
Other investing activities, net	(0.1)	(0.6)
Net Cash Used for Investing Activities	(95.5)	(127.5)
Cash Flows from Financing Activities:
Borrowings of debt	618.0	125.0
Repayments of debt	(127.0)	(85.0)
Payments on financing leases	(0.8)	(1.0)
Debt issuance costs	(1.1)
Repurchases of common stock	(50.0)
Dividends paid	(34.8)	(30.4)
Proceeds from exercise of stock options	0.2	0.6
Shares withheld for employees' income tax obligations	(12.7)	(7.1)
Net Cash Provided by Financing Activities	391.8	2.1
Net Increase (Decrease) in Cash and Cash Equivalents	403.0	(7.5)
Cash and Cash Equivalents, beginning of period	21.0	44.9
Cash and Cash Equivalents, end of period	$ 424.0	$ 37.4

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, 2018	$ 4,949.4	$ 0.6	$ 3,396.1	$ (143.6)	$ 1,693.3	$ 4,946.4	$ 3.0
Beginning Balance (in shares) at Dec. 31, 2018		62.5
Consolidated net earnings	42.9				42.9	42.9
Other comprehensive earnings, net of tax	3.2			3.2		3.2
Dividends declared	(30.4)				(30.4)	(30.4)
Issuances of common stock for stock award plans	3.9		3.9			3.9
Issuances of common stock for stock award plans (in shares)		0.1
Shares withheld for employees' income tax obligations	(7.1)		(7.1)			(7.1)
Stock-based compensation expense	13.5		13.5			13.5
Ending Balance at Mar. 31, 2019	4,975.4	$ 0.6	3,406.4	(140.4)	1,705.8	4,972.4	3.0
Ending Balance (in shares) at Mar. 31, 2019		62.6
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	25.9				25.9	25.9
Other comprehensive earnings, net of tax	0.4			0.4		0.4
Dividends declared	(34.5)				(34.5)	(34.5)
Issuances of common stock for stock award plans	4.5		4.5			4.5
Shares withheld for employees' income tax obligations	(12.7)		(12.7)			(12.7)
Repurchases of common stock	(50.0)				(50.0)	(50.0)
Repurchases of common stock, Shares		(0.2)
Stock-based compensation expense	12.5		12.5			12.5
Ending Balance at Mar. 31, 2020	$ 5,299.4	$ 0.6	$ 3,423.1	$ (145.4)	$ 2,018.6	$ 5,296.9	$ 2.5
Ending Balance (in shares) at Mar. 31, 2020		62.2

Consolidated Statements of Total Equity (Parenthetical) (Unaudited) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Stockholders Equity [Abstract]
Dividends declared	$ 0.55	$ 0.48

Significant Accounting Policies

3 Months Ended

Mar. 31, 2020

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. The Company supplies aggregates (crushed stone, sand and gravel) through its network of approximately 300 quarries, mines and distribution yards in 27 states, Canada and the Bahamas. In the southwestern and western United States, Martin Marietta also provides cement and downstream products, namely, ready mixed concrete, asphalt and paving services, 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 and asphalt and paving product lines are reported collectively as the “Building Materials” business.

Effective January 1, 2020, the Company moved the management of its one quarry in the state of Washington from the Mid-America Group to the West Group, resulting in an immaterial change to its reportable segments. The Company’s Building Materials business includes three reportable segments: the Mid-America Group, the Southeast Group and the West Group.

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

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

The Company has a Magnesia Specialties business with 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, 2019. 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 months ended March 31, 2020 are not indicative of the results expected for other interim periods or the full year. The consolidated balance

sheet at December 31, 2019 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, 2019.

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, including the impact of the coronavirus (COVID-19) pandemic and the related societal response, 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.

New Accounting Pronouncement

Credit Losses

Effective January 1, 2020, the Company adopted Accounting Standards Update (ASU) 2016-13, Financial Instruments – Credit Losses (ASU 2016-13), which includes a current expected credit loss (CECL) model that requires an entity to estimate credit losses expected over the life of an exposure or pool of exposures based on historical information, current information and reasonable and supportable forecasts at the time the asset is recognized and is remeasured at each reporting period. ASU 2016-13 primarily relates to the Company’s receivables, but the scope also includes retainage and contract assets related to its paving business. The adoption of ASU 2016-13 did not have a material impact on the Company’s financial position or statement of earnings and comprehensive earnings. The Company amended its allowance for credit losses policy, which follows, for the implementation of ASU 2016-13.

The Company records an allowance for credit losses, which includes a provision for probable losses based on historical write-offs and a specific reserve for accounts deemed at risk. The allowance is the Company’s estimate for receivables as of the balance sheet date that ultimately will not be collected. Any changes in the allowance are reflected in earnings in the period in which the change occurs. The Company writes-off accounts receivable when it becomes probable, based upon customer facts and circumstances, that such amounts will not be collected.

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Consolidated comprehensive earnings/loss and accumulated other comprehensive loss consist of consolidated net earnings or loss; 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
	March 31,
	2020		2019
	(Dollars in Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Other comprehensive earnings, net of tax		0.4		3.2
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	26.3	$	46.1

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 March 31, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(2.1	)		(2.1	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.5			—			2.5
Other comprehensive earnings (loss), net of tax		2.5			(2.1	)		0.4
Balance at end of period	$	(142.4	)	$	(3.0	)	$	(145.4	)

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141.5	)	$	(2.1	)	$	(143.6	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.7			—			2.7
Other comprehensive earnings, net of tax		2.7			0.5			3.2
Balance at end of period	$	(138.8	)	$	(1.6	)	$	(140.4	)

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

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans

	Three Months Ended March 31, 2020
Balance at beginning of period	$	85.2
Tax effect of other comprehensive earnings		(0.8	)
Balance at end of period	$	84.4

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84.2
Tax effect of other comprehensive earnings		(0.9	)
Balance at end of period	$	83.3

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2020			2019			comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	(0.2	)
Actuarial loss		3.3			3.8
		3.3			3.6		Other nonoperating expenses and (income), net
Tax benefit		(0.8	)		(0.9	)	Income tax expense (benefit)
	$	2.5		$	2.7

Earnings per Common Share

The numerator for basic and diluted earnings per common share is net earnings attributable to Martin Marietta Materials, Inc. 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 months ended March 31, 2020 and 2019, 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
	March 31,
	2020		2019
	(In Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.1
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.8

Basic weighted-average common shares outstanding		62.3		62.6
Effect of dilutive employee and director awards		0.2		0.2
Diluted weighted-average common shares outstanding		62.5		62.8

Revenue Recognition

3 Months Ended

Mar. 31, 2020

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 recognized using the percentage-of-completion method under the revenue-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 21 months. 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 March 31, 2020 and 2019 were $212.7 million and $149.4 million, respectively, where the remaining periods to complete these obligations ranged from one month to 21 months for both periods.

Revenue by Category. The following table presents the Company’s total revenues by category for each reportable segment. Prior-year segment information has been reclassified to conform to the reporting structure change described in Note 1.

	Three Months Ended
	March 31, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	241.0	$	19.8	$	260.8
Southeast Group		116.9		4.2		121.1
West Group		473.2		37.4		510.6
Total Building Materials Business		831.1		61.4		892.5
Magnesia Specialties		59.9		5.8		65.7
Total	$	891.0	$	67.2	$	958.2

	Three Months Ended
	March 31, 2019
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	229.6	$	18.5	$	248.1
Southeast Group		115.3		3.9		119.2
West Group		464.2		33.4		497.6
Total Building Materials Business		809.1		55.8		864.9
Magnesia Specialties		69.2		4.9		74.1
Total	$	878.3	$	60.7	$	939.0

Service revenues, which include paving operations located in Colorado, were $14.5 million and $9.9 million for the three months ended March 31, 2020 and 2019, 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)	March 31, 2020		December 31, 2019
Costs in excess of billings	$	3.8	$	2.8
Billings in excess of costs	$	5.4	$	7.8

Revenues recognized from the beginning balance of contract liabilities for the three months ended March 31, 2020 and 2019 were $4.4 million and $3.8 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 $8.5 million and $10.2 million at March 31, 2020 and December 31, 2019, respectively.

Warranties. The Company’s construction contracts generally contain warranty provisions typically for a period of nine months to one year after project completion and cover materials, design or workmanship defects. Historically, the Company has not experienced material costs for warranties. The ready mixed concrete product line carries longer warranty periods, for which the Company has accrued an estimate of warranty cost based on experience with the type of work and any known risks relative to the project. In total, warranty costs were not material to the Company’s consolidated results of operations for the three months ended March 31, 2020 and 2019.

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.

Inventories, Net

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Inventories, Net

3.	Inventories, Net

	March 31,			December 31,
	2020			2019
	(Dollars in Millions)
Finished products	$	657.1		$	643.6
Products in process		40.2			41.9
Raw materials		36.7			32.4
Supplies and expendable parts		140.5			141.5
		874.5			859.4
Less: Allowances		(174.0	)		(168.6	)
Total	$	700.5		$	690.8

Long-Term Debt

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Long-Term Debt

4.	Long-Term Debt

	March 31,			December 31,
	2020			2019
	(Dollars in Millions)
4.25% Senior Notes, due 2024	$	397.2		$	397.0
7% Debentures, due 2025		124.4			124.4
3.450% Senior Notes, due 2027		297.3			297.3
3.500% Senior Notes, due 2027		495.4			495.3
2.500% Senior Notes, due 2030		489.5			—
6.25% Senior Notes, due 2037		228.2			228.1
4.250% Senior Notes, due 2047		591.7			591.7
Floating Rate Senior Notes, due 2020, interest rate of 2.33% and 2.55% at March 31, 2020 and December 31, 2019, respectively		299.9			299.7
Trade Receivable Facility, interest rate of 2.31% and 2.42% at March 31, 2020 and December 31, 2019, respectively		340.0			340.0
Other notes		0.2			0.1
Total debt		3,263.8			2,773.6
Less: Current maturities of long-term debt and short-term facilities		(639.9	)		(340.0	)
Long-term debt	$	2,623.9		$	2,433.6

On March 5, 2020, the Company issued $500 million aggregate principal amount of 2.500% Senior Notes due 2030 (the 2.500% Senior Notes). The 2.500% Senior Notes are carried net of original issue discount, which is being amortized by the effective interest method over the life of the issue. The 2.500% Senior Notes are redeemable prior to December 15, 2029 at their make-whole redemption price at a discount rate of the U.S. Treasury Rate plus 30 basis points, or on or after December 15, 2029 at a redemption price equal to 100% of the principal amount plus accrued and unpaid interest to the date of redemption. The Company intends to use the net proceeds for general corporate purposes, including the repayment at maturity of $300 million of existing Floating Rate Notes due May 2020, which was classified as current long-term debt on the consolidated balance sheet at March 31, 2020. At December 31, 2019, the Floating Rate Senior Notes due May 2020 were classified as noncurrent long-term debt on the consolidated balance sheet as the Company had the intent and ability to refinance the notes on a long-term basis.

The Company, through a wholly-owned special-purpose subsidiary, has a $400 million trade receivable securitization facility (the Trade Receivable Facility) which matures on September 23, 2020. 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 to the wholly-owned special-purpose subsidiary by the Company. 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 one-month London Interbank Offered Rate, or LIBOR, plus 0.725%, subject to change in the event that this rate no longer reflects the lender’s cost of lending. The Trade Receivable Facility contains a cross-default provision to the Company’s other debt agreements.

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 March 31, 2020 or December 31, 2019. 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 March 31, 2020.

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 $2.3 million of outstanding letters of credit issued under the Revolving Facility at March 31, 2020 and December 31, 2019.

Financial Instruments

3 Months Ended

Mar. 31, 2020

Financial Instruments Disclosure [Abstract]

Financial Instruments

5.	Financial Instruments

The Company’s financial instruments include cash equivalents, accounts receivable, notes receivable, accounts payable, publicly-registered long-term notes, debentures and other long-term debt.

Cash equivalents 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.

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. The estimated fair values of accounts receivable approximate their carrying amounts due to the short-term nature of the receivables.

Notes receivable are not publicly traded. Management estimates that the fair value of notes receivable approximates the carrying amount due to the short-term nature of the receivables.

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 $3.26 billion and $3.23 billion, respectively, at March 31, 2020 and $2.77 billion and $2.94 billion, respectively, at December 31, 2019. The estimated fair value of the publicly-registered long-term notes was estimated based on Level 2 of the fair value hierarchy using quoted market prices. The estimated fair value of other borrowings approximate their carrying amounts as the interest rates reset periodically.

Income Taxes

3 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

6.	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 from the permanent tax benefits associated with the statutory depletion deduction for mineral reserves. For the three months ended March 31, 2020, the low effective income tax rate of 0.6% was primarily attributable to a $6.9 million discrete benefit from financing third-party railroad maintenance. In exchange, the Company received a federal income tax credit and deduction. For the three months ended March 31, 2019, the effective income tax rate included a $13.2 million discrete benefit from a change in the tax status of a subsidiary from a partnership to a corporation, contributing to an overall income tax benefit of $5.0 million.

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.

Pension and Postretirement Benefits

3 Months Ended

Mar. 31, 2020

Compensation And Retirement Disclosure [Abstract]

Pension and Postretirement Benefits

7.	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 March 31,
	2020			2019			2020			2019
	(Dollars in Millions)
Service cost	$	9.7		$	7.9		$	—		$	—
Interest cost		9.2			9.4			0.1			0.1
Expected return on assets		(14.6	)		(12.0	)		—			—
Amortization of:
Prior service cost (credit)		0.2			—			(0.2	)		(0.2	)
Actuarial loss (gain)		3.3			3.9			—			(0.1	)
Net periodic benefit cost (credit)	$	7.8		$	9.2		$	(0.1	)	$	(0.2	)

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 expenses and (income), net, in the consolidated statements of earnings and comprehensive earnings.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

8.	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 the protection of the environment. 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, which court the case is in 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 $11.2 million was outstanding as of March 31, 2020 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 March 31, 2020 and December 31, 2019. 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 March 31, 2020, the Company was contingently liable for $32.9 million in letters of credit, of which $2.3 million were issued under the Company’s Revolving Facility.

Business Segments

3 Months Ended

Mar. 31, 2020

Segment Reporting [Abstract]

Business Segments

9.	Business Segments

The Building Materials business contains three reportable business segments: Mid-America Group, Southeast Group and 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, net; other operating income and expenses, net; and exclude interest expense; other nonoperating income and expenses, net; and taxes on income. Corporate loss from operations primarily includes depreciation on capitalized interest; unallocated expenses for corporate administrative functions; acquisition-related expenses, net; and other nonrecurring income and expenses excluded from the Company’s evaluation of business segment performance and resource allocation. All debt and related interest expense are held at Corporate.

The following table displays selected financial data for the Company’s reportable business 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, which are eliminated. Prior-year segment information has been reclassified to conform to the reporting structure change described in Note 1.

	Three Months Ended
	March 31,
	2020			2019
	(Dollars in Millions)
Total revenues:
Mid-America Group	$	260.8		$	248.1
Southeast Group		121.1			119.2
West Group		510.6			497.6
Total Building Materials Business		892.5			864.9
Magnesia Specialties		65.7			74.1
Total	$	958.2		$	939.0

Products and services revenues:
Mid-America Group	$	241.0		$	229.6
Southeast Group		116.9			115.3
West Group		473.2			464.2
Total Building Materials Business		831.1			809.1
Magnesia Specialties		59.9			69.2
Total	$	891.0		$	878.3

Earnings (Loss) from operations:
Mid-America Group	$	20.8		$	30.6
Southeast Group		14.0			21.1
West Group		22.7			20.3
Total Building Materials Business		57.5			72.0
Magnesia Specialties		21.7			22.6
Corporate		(21.4	)		(25.4	)
Total	$	57.8		$	69.2

Revenues and Gross Profit

3 Months Ended

Mar. 31, 2020

Revenues And Gross Profit [Abstract]

Revenues and Gross Profit

10.	Revenues and Gross Profit

The Building Materials business includes the aggregates, cement, ready mixed concrete and asphalt and paving product lines. All cement, ready mixed concrete and asphalt and paving product lines reside in the West Group. The following table, which is reconciled to consolidated amounts, provides total revenues and gross profit by product line. The Company’s two cold mix asphalt plants have been reclassified from the asphalt and paving product line to the aggregates product line. These operations did not represent a material amount of product revenues and gross profit. Prior-year information has been reclassified to conform to the presentation of the Company’s current reportable product lines.

	Three Months Ended
	March 31,
	2020			2019
	(Dollars in Millions)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	570.3		$	544.9
Cement		106.6			99.0
Ready mixed concrete		189.7			211.2
Asphalt and paving services		18.1			12.4
Less: interproduct revenues		(53.6	)		(58.4	)
Products and services		831.1			809.1
Freight		61.4			55.8
Total Building Materials Business		892.5			864.9
Magnesia Specialties:
Products and services		59.9			69.2
Freight		5.8			4.9
Total Magnesia Specialties		65.7			74.1
Total	$	958.2		$	939.0

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	93.4		$	98.0
Cement		27.3			13.8
Ready mixed concrete		5.9			14.5
Asphalt and paving services		(8.1	)		(8.3	)
Products and services		118.5			118.0
Freight		(0.3	)		(0.2	)
Total Building Materials Business		118.2			117.8
Magnesia Specialties:
Products and services		26.1			26.5
Freight		(0.9	)		(1.0	)
Total Magnesia Specialties		25.2			25.5
Corporate		(1.0	)		(0.4	)
Total	$	142.4		$	142.9

Supplemental Cash Flow Information

3 Months Ended

Mar. 31, 2020

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

11.	Supplemental Cash Flow Information

Noncash investing and financing activities are as follows:

	March 31,
	2020		2019
	(Dollars in Millions)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	21.4	$	20.6
Accrued proceeds from company-owned life insurance benefits	$	0.8	$	—
Acquisition of assets through swap	$	—	$	1.1
Receivable issued in connection with sale of property, plant and equipment	$	—	$	1.3
Right-of-use assets obtained in exchange for new operating lease liabilities	$	12.7	$	16.9
Right-of-use assets obtained in exchange for new finance lease liabilities	$	—	$	0.2

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2020		2019
	(Dollars in Millions)
Cash paid for interest	$	11.9	$	17.8
Cash paid for income taxes	$	1.4	$	3.9

During the quarter ended March 31, 2020, the Company repaid $7.2 million of loans related to its company-owned life insurance policies. The repayment is included in the ‘Investments in life insurance contracts, net’ in the investing activities of the consolidated statement of cash flows.

Other Operating Expenses and (Income), Net

3 Months Ended

Mar. 31, 2020

Other Income And Expenses [Abstract]

Other Operating Expenses and (Income), Net

12.	Other Operating Expenses and (Income), Net

Other operating expenses and (income), net, for the quarter ended March 31, 2020, reflects higher bad debt expense and lower gains on sales of assets compared with the prior-year period. Additionally, other operating expenses and (income), net, for the three months ended March 31, 2019, reflects the reversal of $4.2 million of accruals for unclaimed property contingencies.

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Organization

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

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

Basis of Presentation

New Accounting Pronouncement

Credit Losses

Consolidated Comprehensive Earnings/Loss and Accumulated Other Comprehensive Loss

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2020		2019
	(Dollars in Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Other comprehensive earnings, net of tax		0.4		3.2
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	26.3	$	46.1

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 March 31, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(2.1	)		(2.1	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.5			—			2.5
Other comprehensive earnings (loss), net of tax		2.5			(2.1	)		0.4
Balance at end of period	$	(142.4	)	$	(3.0	)	$	(145.4	)

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141.5	)	$	(2.1	)	$	(143.6	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.7			—			2.7
Other comprehensive earnings, net of tax		2.7			0.5			3.2
Balance at end of period	$	(138.8	)	$	(1.6	)	$	(140.4	)

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

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans

	Three Months Ended March 31, 2020
Balance at beginning of period	$	85.2
Tax effect of other comprehensive earnings		(0.8	)
Balance at end of period	$	84.4

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84.2
Tax effect of other comprehensive earnings		(0.9	)
Balance at end of period	$	83.3

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2020			2019			comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	(0.2	)
Actuarial loss		3.3			3.8
		3.3			3.6		Other nonoperating expenses and (income), net
Tax benefit		(0.8	)		(0.9	)	Income tax expense (benefit)
	$	2.5		$	2.7

Earnings per Common Share

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

	Three Months Ended
	March 31,
	2020		2019
	(In Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.1
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.8

Basic weighted-average common shares outstanding		62.3		62.6
Effect of dilutive employee and director awards		0.2		0.2
Diluted weighted-average common shares outstanding		62.5		62.8

Policy Elections

Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2020

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 March 31, 2020
Balance at beginning of period	$	(144.9	)	$	(0.9	)	$	(145.8	)
Other comprehensive loss before reclassifications, net of tax		—			(2.1	)		(2.1	)
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.5			—			2.5
Other comprehensive earnings (loss), net of tax		2.5			(2.1	)		0.4
Balance at end of period	$	(142.4	)	$	(3.0	)	$	(145.4	)

	Three Months Ended March 31, 2019
Balance at beginning of period	$	(141.5	)	$	(2.1	)	$	(143.6	)
Other comprehensive earnings before reclassifications, net of tax		—			0.5			0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax		2.7			—			2.7
Other comprehensive earnings, net of tax		2.7			0.5			3.2
Balance at end of period	$	(138.8	)	$	(1.6	)	$	(140.4	)

Noncurrent Deferred Tax Assets Recorded In Accumulated Other Comprehensive Loss

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

	(Dollars in Millions)
	Pension and Postretirement Benefit Plans

	Three Months Ended March 31, 2020
Balance at beginning of period	$	85.2
Tax effect of other comprehensive earnings		(0.8	)
Balance at end of period	$	84.4

	Three Months Ended March 31, 2019
Balance at beginning of period	$	84.2
Tax effect of other comprehensive earnings		(0.9	)
Balance at end of period	$	83.3

Reclassification Out of Accumulated Other Comprehensive Loss

Reclassifications out of accumulated other comprehensive loss are as follows:

	Three Months Ended						Affected line items in the consolidated
	March 31,						statements of earnings and
	2020			2019			comprehensive earnings
	(Dollars in Millions)
Pension and postretirement benefit plans
Amortization of:
Prior service credit	$	—		$	(0.2	)
Actuarial loss		3.3			3.8
		3.3			3.6		Other nonoperating expenses and (income), net
Tax benefit		(0.8	)		(0.9	)	Income tax expense (benefit)
	$	2.5		$	2.7

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
	March 31,
	2020		2019
	(In Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Less: Distributed and undistributed earnings attributable to unvested awards		—		0.1
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.8

Basic weighted-average common shares outstanding		62.3		62.6
Effect of dilutive employee and director awards		0.2		0.2
Diluted weighted-average common shares outstanding		62.5		62.8

Parent

Significant Accounting Policies [Line Items]

Comprehensive Earnings

Comprehensive earnings attributable to Martin Marietta is as follows:

	Three Months Ended
	March 31,
	2020		2019
	(Dollars in Millions)
Net earnings attributable to Martin Marietta Materials, Inc.	$	25.9	$	42.9
Other comprehensive earnings, net of tax		0.4		3.2
Comprehensive earnings attributable to Martin Marietta Materials, Inc.	$	26.3	$	46.1

Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2020

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. Prior-year segment information has been reclassified to conform to the reporting structure change described in Note 1.

	Three Months Ended
	March 31, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	241.0	$	19.8	$	260.8
Southeast Group		116.9		4.2		121.1
West Group		473.2		37.4		510.6
Total Building Materials Business		831.1		61.4		892.5
Magnesia Specialties		59.9		5.8		65.7
Total	$	891.0	$	67.2	$	958.2

	Three Months Ended
	March 31, 2019
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	229.6	$	18.5	$	248.1
Southeast Group		115.3		3.9		119.2
West Group		464.2		33.4		497.6
Total Building Materials Business		809.1		55.8		864.9
Magnesia Specialties		69.2		4.9		74.1
Total	$	878.3	$	60.7	$	939.0

Summary of Information About the Company's Contract Balances

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

(Dollars in Millions)	March 31, 2020		December 31, 2019
Costs in excess of billings	$	3.8	$	2.8
Billings in excess of costs	$	5.4	$	7.8

Inventories, Net (Tables)

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Schedule of Inventories Net

	March 31,			December 31,
	2020			2019
	(Dollars in Millions)
Finished products	$	657.1		$	643.6
Products in process		40.2			41.9
Raw materials		36.7			32.4
Supplies and expendable parts		140.5			141.5
		874.5			859.4
Less: Allowances		(174.0	)		(168.6	)
Total	$	700.5		$	690.8

Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Long-Term Debt

	March 31,			December 31,
	2020			2019
	(Dollars in Millions)
4.25% Senior Notes, due 2024	$	397.2		$	397.0
7% Debentures, due 2025		124.4			124.4
3.450% Senior Notes, due 2027		297.3			297.3
3.500% Senior Notes, due 2027		495.4			495.3
2.500% Senior Notes, due 2030		489.5			—
6.25% Senior Notes, due 2037		228.2			228.1
4.250% Senior Notes, due 2047		591.7			591.7
Floating Rate Senior Notes, due 2020, interest rate of 2.33% and 2.55% at March 31, 2020 and December 31, 2019, respectively		299.9			299.7
Trade Receivable Facility, interest rate of 2.31% and 2.42% at March 31, 2020 and December 31, 2019, respectively		340.0			340.0
Other notes		0.2			0.1
Total debt		3,263.8			2,773.6
Less: Current maturities of long-term debt and short-term facilities		(639.9	)		(340.0	)
Long-term debt	$	2,623.9		$	2,433.6

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Pension and Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2020

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 March 31,
	2020			2019			2020			2019
	(Dollars in Millions)
Service cost	$	9.7		$	7.9		$	—		$	—
Interest cost		9.2			9.4			0.1			0.1
Expected return on assets		(14.6	)		(12.0	)		—			—
Amortization of:
Prior service cost (credit)		0.2			—			(0.2	)		(0.2	)
Actuarial loss (gain)		3.3			3.9			—			(0.1	)
Net periodic benefit cost (credit)	$	7.8		$	9.2		$	(0.1	)	$	(0.2	)

Business Segments (Tables)

3 Months Ended

Mar. 31, 2020

Segment Reporting [Abstract]

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

	Three Months Ended
	March 31,
	2020			2019
	(Dollars in Millions)
Total revenues:
Mid-America Group	$	260.8		$	248.1
Southeast Group		121.1			119.2
West Group		510.6			497.6
Total Building Materials Business		892.5			864.9
Magnesia Specialties		65.7			74.1
Total	$	958.2		$	939.0

Products and services revenues:
Mid-America Group	$	241.0		$	229.6
Southeast Group		116.9			115.3
West Group		473.2			464.2
Total Building Materials Business		831.1			809.1
Magnesia Specialties		59.9			69.2
Total	$	891.0		$	878.3

Earnings (Loss) from operations:
Mid-America Group	$	20.8		$	30.6
Southeast Group		14.0			21.1
West Group		22.7			20.3
Total Building Materials Business		57.5			72.0
Magnesia Specialties		21.7			22.6
Corporate		(21.4	)		(25.4	)
Total	$	57.8		$	69.2

Revenues and Gross Profit (Tables)

3 Months Ended

Mar. 31, 2020

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
	March 31,
	2020			2019
	(Dollars in Millions)
Total revenues:
Building Materials Business:
Products and services:
Aggregates	$	570.3		$	544.9
Cement		106.6			99.0
Ready mixed concrete		189.7			211.2
Asphalt and paving services		18.1			12.4
Less: interproduct revenues		(53.6	)		(58.4	)
Products and services		831.1			809.1
Freight		61.4			55.8
Total Building Materials Business		892.5			864.9
Magnesia Specialties:
Products and services		59.9			69.2
Freight		5.8			4.9
Total Magnesia Specialties		65.7			74.1
Total	$	958.2		$	939.0

Gross profit (loss):
Building Materials Business:
Products and services:
Aggregates	$	93.4		$	98.0
Cement		27.3			13.8
Ready mixed concrete		5.9			14.5
Asphalt and paving services		(8.1	)		(8.3	)
Products and services		118.5			118.0
Freight		(0.3	)		(0.2	)
Total Building Materials Business		118.2			117.8
Magnesia Specialties:
Products and services		26.1			26.5
Freight		(0.9	)		(1.0	)
Total Magnesia Specialties		25.2			25.5
Corporate		(1.0	)		(0.4	)
Total	$	142.4		$	142.9

Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2020

Supplemental Cash Flow Elements [Abstract]

Schedule Of Other Significant Noncash Transactions

Noncash investing and financing activities are as follows:

	March 31,
	2020		2019
	(Dollars in Millions)
Noncash investing and financing activities:
Accrued liabilities for purchases of property, plant and equipment	$	21.4	$	20.6
Accrued proceeds from company-owned life insurance benefits	$	0.8	$	—
Acquisition of assets through swap	$	—	$	1.1
Receivable issued in connection with sale of property, plant and equipment	$	—	$	1.3
Right-of-use assets obtained in exchange for new operating lease liabilities	$	12.7	$	16.9
Right-of-use assets obtained in exchange for new finance lease liabilities	$	—	$	0.2

Supplemental Disclosures of Cash Flow Information

Supplemental disclosures of cash flow information are as follows:

	March 31,
	2020		2019
	(Dollars in Millions)
Cash paid for interest	$	11.9	$	17.8
Cash paid for income taxes	$	1.4	$	3.9

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020 Facility State Segment
Accounting Policies [Abstract]
Number of quarries and yards \| Facility	300
Number of states with aggregates business sales by destination \| State	27
Reportable business segments \| Segment	3

Significant Accounting Policies - Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 25.9	$ 42.9
Other comprehensive earnings, net of tax	0.4	3.2
Earnings attributable to Martin Marietta Materials, Inc.	$ 26.3	$ 46.1

- 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 - Changes in Accumulated Other Comprehensive Loss Net of Tax (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 5,353.3	$ 4,949.4
Other comprehensive earnings (loss), net of tax	0.4	3.2
Ending Balance	5,299.4	4,975.4
Pension and Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(144.9)	(141.5)
Amounts reclassified from accumulated other comprehensive loss, net of tax	2.5	2.7
Other comprehensive earnings (loss), net of tax	2.5	2.7
Ending Balance	(142.4)	(138.8)
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(0.9)	(2.1)
Other comprehensive earnings (loss) before reclassifications, net of tax	(2.1)	0.5
Other comprehensive earnings (loss), net of tax	(2.1)	0.5
Ending Balance	(3.0)	(1.6)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(145.8)	(143.6)
Other comprehensive earnings (loss) before reclassifications, net of tax	(2.1)	0.5
Amounts reclassified from accumulated other comprehensive loss, net of tax	2.5	2.7
Other comprehensive earnings (loss), net of tax	0.4	3.2
Ending Balance	$ (145.4)	$ (140.4)

Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 85.2	$ 84.2
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(0.8)	(0.9)
Balance at end of period, Pension and Postretirement Benefit Plans	$ 84.4	$ 83.3

Significant Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Additional interest expense	$ 29.8	$ 32.9
Tax benefit	0.1	(5.0)
Pension and Postretirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings from Continuing Operations	2.5	2.7
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		(0.2)
Actuarial loss	3.3	3.8
Tax benefit	(0.8)	(0.9)
Earnings from Continuing Operations	2.5	2.7
Reclassification out of Accumulated Other Comprehensive Income \| Pension and Postretirement Benefit Plans \| Other Nonoperating Expense and (Income), Net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications out of accumulated other comprehensive loss before taxes	$ 3.3	$ 3.6

Significant Accounting Policies - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net earnings attributable to Martin Marietta Materials, Inc.	$ 25.9	$ 42.9
Less: Distributed and undistributed earnings attributable to unvested awards		0.1
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	$ 25.9	$ 42.8
Basic weighted-average common shares outstanding	62.3	62.6
Effect of dilutive employee and director awards	0.2	0.2
Diluted weighted-average common shares outstanding	62.5	62.8

- Definition

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

+ References + Details

Revenue Recognition - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
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 21 months. 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	$ 212.7	$ 149.4
Service revenues	958.2	939.0
Revenue recognized from contract liabilities	4.4	3.8
Retainage on contracts	8.5		$ 10.2
Service \| COLORADO
Revenue Recognition [Line Items]
Service revenues	$ 14.5	$ 9.9
Minimum
Revenue Recognition [Line Items]
Warranty term	9 months	9 months
Minimum \| Service
Revenue Recognition [Line Items]
Performance obligations, period	1 day
Maximum
Revenue Recognition [Line Items]
Warranty term	1 year	1 year
Maximum \| Service
Revenue Recognition [Line Items]
Performance obligations, period	21 months

Revenue Recognition - Additional Information (Detail 1)	Mar. 31, 2020	Mar. 31, 2019
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		1 month
Minimum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period	1 month
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Revenue Recognition [Line Items]
Performance obligations, customer satisfaction period		21 months
Maximum \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
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
	Mar. 31, 2020	Mar. 31, 2019
Revenue Recognition [Line Items]
Total	$ 958.2	$ 939.0
Building Materials Business
Revenue Recognition [Line Items]
Total	892.5	864.9
Products and Services
Revenue Recognition [Line Items]
Total	891.0	878.3
Products and Services \| Building Materials Business
Revenue Recognition [Line Items]
Total	831.1	809.1
Freight
Revenue Recognition [Line Items]
Total	67.2	60.7
Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	61.4	55.8
Operating Segments \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	260.8	248.1
Operating Segments \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	121.1	119.2
Operating Segments \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	510.6	497.6
Operating Segments \| Building Materials Business
Revenue Recognition [Line Items]
Total	892.5	864.9
Operating Segments \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	65.7	74.1
Operating Segments \| Products and Services \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	241.0	229.6
Operating Segments \| Products and Services \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	116.9	115.3
Operating Segments \| Products and Services \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	473.2	464.2
Operating Segments \| Products and Services \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	59.9	69.2
Operating Segments \| Freight \| Building Materials Business Mid-America Group
Revenue Recognition [Line Items]
Total	19.8	18.5
Operating Segments \| Freight \| Building Materials Business Southeast Group
Revenue Recognition [Line Items]
Total	4.2	3.9
Operating Segments \| Freight \| Building Materials Business West Group
Revenue Recognition [Line Items]
Total	37.4	33.4
Operating Segments \| Freight \| Building Materials Business
Revenue Recognition [Line Items]
Total	61.4	55.8
Operating Segments \| Freight \| Magnesia Specialties
Revenue Recognition [Line Items]
Total	$ 5.8	$ 4.9

Revenue Recognition - Summary of Information About the Company's Contract Balances (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Costs in excess of billings	$ 3.8	$ 2.8
Billings in excess of costs	$ 5.4	$ 7.8

Inventories, Net - Schedule of Inventories Net (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished products	$ 657.1	$ 643.6
Products in process	40.2	41.9
Raw materials	36.7	32.4
Supplies and expendable parts	140.5	141.5
Inventories, Gross	874.5	859.4
Less: Allowances	(174.0)	(168.6)
Total	$ 700.5	$ 690.8

Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total debt	$ 3,263.8	$ 2,773.6
Less: Current maturities of long-term debt and short-term facilities	(639.9)	(340.0)
Long-term debt	2,623.9	2,433.6
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	397.2	397.0
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124.4	124.4
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	297.3	297.3
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	495.4	495.3
2.500% Senior Notes, Due 2030
Debt Instrument [Line Items]
Total debt	489.5
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228.2	228.1
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total debt	591.7	591.7
Floating Rate Senior Notes, Due 2020
Debt Instrument [Line Items]
Total debt	299.9	299.7
Other Notes
Debt Instrument [Line Items]
Total debt	0.2	0.1
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	$ 340.0	$ 340.0

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail)		3 Months Ended
	Mar. 05, 2020	Mar. 31, 2020	Dec. 31, 2019
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	2030
Interest rate on notes	2.50%	2.50%
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%
Floating Rate Senior Notes, Due 2020
Debt Instrument [Line Items]
Maturity year		2020
Interest rate		2.33%	2.55%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate		2.31%	2.42%

Long-Term Debt - Additional Information (Detail) - USD ($)			3 Months Ended
	Mar. 05, 2020	Sep. 24, 2019	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Debt instrument redemption price percentage	100.00%
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation			$ 200,000,000
Outstanding letters of credit			32,900,000
Minimum
Debt Instrument [Line Items]
Reduction of consolidated debt in the debt ratio calculation			$ 50,000,000
Including Acquisition Bridge Debt \| Maximum
Debt Instrument [Line Items]
Debt covenant			3.50
Excluding Acquisition Bridge Debt \| Maximum
Debt Instrument [Line Items]
Debt covenant			3.75
Revolving Facility
Debt Instrument [Line Items]
Credit facility commitment			$ 700,000,000
Debt instrument maturity period			Dec. 05, 2024
Senior unsecured revolving facility, maturity period			5 years
Revolving facility, borrowings outstanding			$ 0	$ 0
Outstanding letters of credit			$ 2,300,000	$ 2,300,000
US Treasury (UST) Interest Rate
Debt Instrument [Line Items]
Basis spread on variable rate	30.00%
2.500% Senior Notes, Due 2030
Debt Instrument [Line Items]
Aggregate principal amount of long term debt	$ 500,000,000
Interest rate on notes	2.50%		2.50%
Maturity year	2030		2030
Floating Rate Senior Notes, Due 2020
Debt Instrument [Line Items]
Maturity year			2020
Trade Receivable Facility
Debt Instrument [Line Items]
Credit facility commitment			$ 400,000,000
Debt instrument maturity period		Sep. 23, 2020
Trade Receivable Facility \| London Interbank Offered Rate(LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate			0.725%
Current Long-term Debt \| Floating Rate Senior Notes, Due 2020
Debt Instrument [Line Items]
Debt Instrument Payable Upon Maturity	$ 300,000,000

Financial Instruments - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) Customer	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Long-term debt, carrying values	$ 3,263.8	$ 2,773.6
Long-term debt, fair values	$ 3,230.0	$ 2,940.0
Customer Concentration Risk \| Total Revenues
Debt Instrument [Line Items]
Number of customer accounted for 10% or more of consolidated total revenues \| Customer	0
Customer Concentration Risk \| Total Revenues \| Minimum
Debt Instrument [Line Items]
Percentage of concentration risk	10.00%

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Effective change in income tax rate	0.60%
Discrete benefit from change in tax status of subsidiary from partnership to corporation	$ 6.9	$ 13.2
Income tax expense (benefit)	$ 0.1	$ (5.0)

Pension and Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9.7	$ 7.9
Interest cost	9.2	9.4
Expected return on assets	(14.6)	(12.0)
Prior service cost (credit)	0.2
Actuarial loss (gain)	3.3	3.9
Net periodic benefit cost (credit)	7.8	9.2
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.1	0.1
Prior service cost (credit)	(0.2)	(0.2)
Actuarial loss (gain)		(0.1)
Net periodic benefit cost (credit)	$ (0.1)	$ (0.2)

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies [Line Items]
Guarantee of affiliate's obligations	$ 12,500,000
Due from affiliate	11,200,000
Outstanding letters of credit	32,900,000
Revolving Facility
Commitments and Contingencies [Line Items]
Outstanding letters of credit	2,300,000	$ 2,300,000
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)	3 Months Ended
Business Segments - Additional Information (Detail)	Mar. 31, 2020 Segment
Segment Reporting [Abstract]
Reportable business segments	3

Business Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 958.2	$ 939.0
Earnings (Loss) from operations	57.8	69.2
Products and Services
Segment Reporting Information [Line Items]
Total revenues	891.0	878.3
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	892.5	864.9
Earnings (Loss) from operations	57.5	72.0
Building Materials Business \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	831.1	809.1
Operating Segments \| Building Materials Business Mid-America Group
Segment Reporting Information [Line Items]
Total revenues	260.8	248.1
Earnings (Loss) from operations	20.8	30.6
Operating Segments \| Building Materials Business Mid-America Group \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	241.0	229.6
Operating Segments \| Building Materials Business Southeast Group
Segment Reporting Information [Line Items]
Total revenues	121.1	119.2
Earnings (Loss) from operations	14.0	21.1
Operating Segments \| Building Materials Business Southeast Group \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	116.9	115.3
Operating Segments \| Building Materials Business West Group
Segment Reporting Information [Line Items]
Total revenues	510.6	497.6
Earnings (Loss) from operations	22.7	20.3
Operating Segments \| Building Materials Business West Group \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	473.2	464.2
Operating Segments \| Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues	65.7	74.1
Earnings (Loss) from operations	21.7	22.6
Operating Segments \| Magnesia Specialties \| Products and Services
Segment Reporting Information [Line Items]
Total revenues	59.9	69.2
Operating Segments \| Building Materials Business
Segment Reporting Information [Line Items]
Total revenues	892.5	864.9
Corporate
Segment Reporting Information [Line Items]
Earnings (Loss) from operations	$ (21.4)	$ (25.4)

Revenues and Gross Profit - Total Revenues and Gross Profit by Product Line (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Product Information [Line Items]
Total revenues	$ 958.2	$ 939.0
Gross profit (loss)	142.4	142.9
Interproduct Revenues
Product Information [Line Items]
Total revenues	(53.6)	(58.4)
Corporate
Product Information [Line Items]
Gross profit (loss)	(1.0)	(0.4)
Building Materials Business
Product Information [Line Items]
Total revenues	892.5	864.9
Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	892.5	864.9
Gross profit (loss)	118.2	117.8
Building Materials Business \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	831.1	809.1
Gross profit (loss)	118.5	118.0
Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	65.7	74.1
Gross profit (loss)	25.2	25.5
Magnesia Specialties \| Operating Segments \| Products and Services
Product Information [Line Items]
Total revenues	59.9	69.2
Gross profit (loss)	26.1	26.5
Aggregates \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	570.3	544.9
Gross profit (loss)	93.4	98.0
Cement \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	106.6	99.0
Gross profit (loss)	27.3	13.8
Ready Mixed Concrete \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	189.7	211.2
Gross profit (loss)	5.9	14.5
Asphalt and Paving \| Building Materials Business \| Operating Segments \| Reportable Subsegments \| Products and Services
Product Information [Line Items]
Total revenues	18.1	12.4
Gross profit (loss)	(8.1)	(8.3)
Freight
Product Information [Line Items]
Total revenues	67.2	60.7
Freight \| Building Materials Business
Product Information [Line Items]
Total revenues	61.4	55.8
Freight \| Building Materials Business \| Operating Segments
Product Information [Line Items]
Total revenues	61.4	55.8
Gross profit (loss)	(0.3)	(0.2)
Freight \| Magnesia Specialties \| Operating Segments
Product Information [Line Items]
Total revenues	5.8	4.9
Gross profit (loss)	$ (0.9)	$ (1.0)

Supplemental Cash Flow Information - Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 21.4	$ 20.6
Accrued proceeds from company-owned life insurance benefits	0.8
Acquisition of assets through swap		1.1
Receivable issued in connection with sale of property, plant and equipment		1.3
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 12.7	16.9
Right-of-use assets obtained in exchange for new finance lease liabilities		$ 0.2

Supplemental Cash Flow Information -Supplemental Disclosures of Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 11.9	$ 17.8
Cash paid for income taxes	$ 1.4	$ 3.9

Supplemental Cash Flow Information - Narrative (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Supplemental Cash Flow Elements [Abstract]
Repayment of loans related to life insurance policies	$ 7.2

Other Operating Expenses and (Income), Net - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Other Income And Expenses [Abstract]
Reversal of accruals for unclaimed property contingencies	$ 4.2