Derivative Financial Instruments - Derivative Notional Values (Detail) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Derivative [Line Items]
Total Derivative Notional Values	$ 8,700,000,000	$ 10,300,000,000
Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,000,000,000	2,200,000,000
Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	6,100,000,000	6,200,000,000
Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,600,000,000	1,900,000,000
Interest Rate Swaps [Member]
Derivative [Line Items]
Total Derivative Notional Values	7,200,000,000	8,700,000,000
Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Cash Flow [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,000,000,000	2,200,000,000
Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member] | Fair Value [Member]
Derivative [Line Items]
Total Derivative Notional Values	4,600,000,000	4,600,000,000
Interest Rate Swaps [Member] | Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,600,000,000	1,900,000,000
Floor Income Contracts [Member]
Derivative [Line Items]
Total Derivative Notional Values	0	0
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	0
Cross-Currency Interest Rate Swaps [Member]
Derivative [Line Items]
Total Derivative Notional Values	1,500,000,000	1,600,000,000
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	1,500,000,000	1,600,000,000
Cross-Currency Interest Rate Swaps [Member] | Trading [Member]
Derivative [Line Items]
Total Derivative Notional Values	$ 0	$ 0