Significant Accounting Policies - Comprehensive Earnings (Loss) Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 348.3	$ 366.5	$ 469.7	$ 387.9
Other comprehensive earnings (loss), net of tax	1.7	1.2	2.8	(30.5)
Consolidated comprehensive earnings attributable to Martin Marietta	$ 350.0	$ 367.7	$ 472.5	$ 357.4