Consolidated Statements of Earnings and Comprehensive Earnings (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total Revenues	$ 1,321.4	$ 1,420.2	$ 3,550.3	$ 3,638.7
Total Cost of Revenues	916.9	999.6	2,622.9	2,718.3
Gross Profit	404.5	420.6	927.4	920.4
Selling, general & administrative expenses	71.1	78.2	221.0	228.9
Acquisition-related expenses	0.4		1.2	0.2
Other operating income, net	(67.6)	(2.9)	(59.6)	(9.1)
Earnings from Operations	400.6	345.3	764.8	700.4
Interest expense	28.7	32.4	89.7	98.7
Other nonoperating (income) and expenses, net	(4.0)	(1.9)	(5.9)	9.7
Earnings before income tax expense	375.9	314.8	681.0	592.0
Income tax expense	81.5	66.2	143.0	111.1
Consolidated net earnings	294.4	248.6	538.0	480.9
Net Earnings Attributable to Martin Marietta Materials, Inc.	294.4	248.6	538.0	480.9
Consolidated Comprehensive Earnings:
Earnings attributable to Martin Marietta Materials, Inc.	298.0	251.1	545.2	489.7
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 298.0	$ 251.1	$ 545.2	$ 489.7
Net Earnings Attributable to Martin Marietta Materials, Inc. Per Common Share:
Basic attributable to common shareholders	$ 4.72	$ 3.97	$ 8.63	$ 7.67
Diluted attributable to common shareholders	$ 4.71	$ 3.96	$ 8.61	$ 7.65
Weighted-Average Common Shares Outstanding:
Basic	62.3	62.5	62.3	62.6
Diluted	62.4	62.7	62.4	62.7
Products and Services
Total Revenues	$ 1,240.7	$ 1,323.2	$ 3,321.2	$ 3,397.6
Total Cost of Revenues	836.1	901.8	2,390.9	2,474.4
Freight
Total Revenues	80.7	97.0	229.1	241.1
Total Cost of Revenues	$ 80.8	$ 97.8	$ 232.0	$ 243.9