Derivatives, Hedging Activities and Interest Expense - Components of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments Gain Loss [Line Items]
Interest expense on debt	$ 1,189	$ 623	$ 2,275	$ 1,069
Interest income on derivatives	(205)	(120)	(414)	(182)
Interest expense on debt and derivatives	984	503	1,861	887
Gains on debt denominated in foreign currencies	(280)	(590)	(243)	(1,181)
Losses on foreign currency swaps	253	743	297	1,456
Total interest expense	1,272	705	2,171	1,268
Interest Expense
Derivative Instruments Gain Loss [Line Items]
Losses on U.S. dollar interest rate swaps	$ 315	$ 49	$ 256	$ 106