Significant Accounting Policies - Comprehensive Earnings (Loss) Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 416.7	$ 295.3	$ 886.4	$ 683.2
Other comprehensive earnings (loss), net of tax	0.4	3.0	3.2	(27.5)
Consolidated comprehensive earnings attributable to Martin Marietta	$ 417.1	$ 298.3	$ 889.6	$ 655.7