Income Taxes - Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Current:
Federal	$ 3	$ (50)	$ 392
State	16	42	16
Foreign	167	218	247
Total Current	186	210	655
Deferred:
Federal	(125)	95	(899)
State	17	23	(59)
Foreign	52	(40)	61
Total Deferred	(56)	78	(897)
Total income tax (benefit) expense	$ 130	$ 288	$ (242)