Unsecured Borrowings - Unsecured Long-Term Borrowings (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Fixed-rate obligations	$ 140,165	$ 157,524
Floating-rate obligations	83,859	89,614
Total	$ 224,024	247,138
Unsecured long term borrowings, maturities, end of range	2061
Unsecured Debt
Debt Instrument [Line Items]
Total	$ 224,024
U.S. Dollar
Debt Instrument [Line Items]
Fixed-rate obligations	107,989	118,986
Floating-rate obligations	50,834	55,689
Total	$ 158,823	$ 174,675
U.S. Dollar | Minimum | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	0.86%	0.66%
U.S. Dollar | Maximum | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	6.75%	6.75%
U.S. Dollar | Weighted Average | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	3.62%	3.51%
Non-U.S. Dollar
Debt Instrument [Line Items]
Fixed-rate obligations	$ 32,176	$ 38,538
Floating-rate obligations	33,025	33,925
Total	$ 65,201	$ 72,463
Non-U.S. Dollar | Minimum | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	0.25%	0.13%
Non-U.S. Dollar | Maximum | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	7.25%	7.25%
Non-U.S. Dollar | Weighted Average | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	2.08%	1.85%