Derivatives, Hedging Activities and Interest Expense - Components of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments Gain Loss [Line Items]
Interest expense on debt	$ 362	$ 460	$ 1,134	$ 1,531
Interest expense on derivatives	23	103	137	334
Interest expense on debt and derivatives	385	563	1,271	1,865
(Gains) losses on debt denominated in foreign currencies	(60)	655	(338)	1,703
Losses (gains) on foreign currency swaps	151	(658)	509	(1,754)
Total interest expense	346	491	1,055	1,534
Interest Expense
Derivative Instruments Gain Loss [Line Items]
Gains on U.S. dollar interest rate swaps	$ (130)	$ (69)	$ (387)	$ (280)