Income Taxes - Reconciliation Between Effective Tax Rate On Income From Continuing Operations And Statutory Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense at federal statutory rate	$ 240	$ 128	$ 75
State income taxes, net of federal tax benefit	(41)	70	50
Tax effect of foreign operations	(81)	(86)	(146)
Unrecognized tax benefits and settlements	(7)	20	454
Non-deductible goodwill	7	357	585
Share-based compensation	2	4	(8)
Net tax benefit on intellectual property transfer	0	(42)	(178)
Tax-free gain on investment exit	(87)	0	0
Impact of change in U.S. tax rate on temporary differences	0	(81)	(1,324)
Transition tax on foreign earnings	0	(5)	457
Capital loss carryback	(19)	0	0
Other, net	4	(9)	(18)
Income tax expense (benefit)	$ 18	$ 356	$ (53)