Debt and Credit Facilities - Debt and Related Weighted Average Contractual Interest Rates (Details) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024
Debt Instrument [Line Items]
Debt, Face value	$ 128,261	$ 122,963
Debt, Carrying value	$ 127,745	$ 122,420
Weighted average contractual interest rates	4.21%	4.32%
Unsecured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt, Face value	$ 90,496	$ 88,576
Debt, Carrying value	$ 90,028	$ 88,083
Weighted average contractual interest rates	4.08%	4.19%
Secured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt, Face value	$ 37,765	$ 34,387
Debt, Carrying value	$ 37,717	$ 34,337
Weighted average contractual interest rates	4.53%	4.64%