Derivative Financial Instruments - Derivative Notional Values (Detail) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Total Derivative Notional Values	$ 10,300,000,000	$ 39,700,000,000
Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	2,200,000,000	8,300,000,000
Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	6,200,000,000	8,000,000,000
Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,900,000,000	23,400,000,000
Interest Rate Swaps [Member]
Derivative [Line Items]
Total Derivative Notional Values	8,700,000,000	31,900,000,000
Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	2,200,000,000	8,300,000,000
Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	4,600,000,000	6,200,000,000
Interest Rate Swaps [Member] | Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,900,000,000	17,400,000,000
Floor Income Contracts [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	6,000,000,000
Floor Income Contracts [Member] | Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	0
Floor Income Contracts [Member] | Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	0
Floor Income Contracts [Member] | Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	6,000,000,000
Cross-Currency Interest Rate Swaps [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,600,000,000	1,800,000,000
Cross-Currency Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	0
Cross-Currency Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,600,000,000	1,800,000,000
Cross-Currency Interest Rate Swaps [Member] | Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	$ 0	$ 0