Derivatives, Hedging Activities and Interest Expense - Components of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Derivative Instruments Gain Loss [Line Items]
Interest expense on debt	$ 1,405	$ 1,087
Interest income on derivatives	(58)	(209)
Interest expense on debt and derivatives	1,347	878
Losses on debt denominated in foreign currencies	20	36
Losses on foreign currency swaps	7	44
Losses (gains) on U.S. dollar interest rate swaps	69	(59)
Total interest expense	$ 1,443	$ 899