Intangible Assets - Components of Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 268	$ 290	$ 815	$ 929
Intangible asset amortization
Finite-Lived Intangible Assets [Line Items]
Amortization expense	212	224	649	735
Transition and transformation contract cost amortization
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 56	$ 66	$ 166	$ 194