Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Operating lease expense
Operating lease cost	$ 117	$ 156	$ 371	$ 463
Short-term lease cost	9	14	32	40
Variable lease cost	17	17	50	40
Sublease income	(1)	(10)	(27)	(32)
Total operating costs	142	177	426	511
Finance lease expense
Amortization of right-of-use assets	85	107	271	322
Interest on lease liabilities	6	10	22	35
Total finance lease cost	$ 91	$ 117	$ 293	$ 357