Significant Accounting Policies - Comprehensive Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 328	$ 294	$ 444	$ 1,339
Other comprehensive earnings, net of tax	3	1	4	1
Consolidated comprehensive earnings attributable to Martin Marietta	$ 331	$ 295	$ 448	$ 1,340