Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Current
Federal	$ 706	$ 769	$ (1,859)
State	115	114	(1)
Foreign	3	12	16
Total	824	895	(1,844)
Deferred
Federal	(258)	(376)	2,100
State	(47)	(72)	78
Foreign	3	(5)	(5)
Total	(302)	(453)	2,173
Provision for income taxes	$ 522	$ 442	$ 329