Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Current
Federal	$ 1,774	$ 2,756	$ (19)
State	281	386	120
Foreign	22	11	8
Total	2,077	3,153	109
Deferred
Federal	(1,166)	(2,243)	145
State	(123)	(276)	(141)
Foreign	1	(2)	(2)
Total	(1,288)	(2,521)	2
Provision for income taxes	$ 789	$ 632	$ 111