Debt and Credit Facilities - Debt and Related Weighted Average Contractual Interest Rates (Details) - USD ($) $ in Millions	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Debt, Face value	$ 109,449	$ 110,015
Debt, Carrying value	$ 109,152	$ 109,725
Weighted average contractual interest rates	1.23%	1.31%
Unsecured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt, Face value	$ 82,542	$ 85,759
Debt, Carrying value	$ 82,288	$ 85,513
Weighted average contractual interest rates	1.30%	1.31%
Secured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt, Face value	$ 26,907	$ 24,256
Debt, Carrying value	$ 26,864	$ 24,212
Weighted average contractual interest rates	1.01%	1.29%