Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 76,000,000	$ 93,000,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	76,000,000	93,000,000
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	95,000,000	114,000,000
Derivative Liabilities Gross Amount Of Collateral Cash And Securities Pledged Not Offset		113,000,000
Fair value of derivative liabilities	93,000,000
Net Amount, Derivative Assets	76,000,000	93,000,000
Net Amount, Derivative Liabilities	2,000,000	1,000,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Derivative Liability, Fair Value, Gross Liability	95,000,000	114,000,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	38,000,000	41,000,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	38,000,000	41,000,000
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,940,000,000	1,835,000,000
Derivative Liabilities Gross Amount Of Collateral Cash And Securities Pledged Not Offset		0
Fair value of derivative liabilities	0
Net Amount, Derivative Assets	38,000,000	41,000,000
Net Amount, Derivative Liabilities	1,940,000,000	1,835,000,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Derivative Liability, Fair Value, Gross Liability	1,940,000,000	1,835,000,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Other Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	0	0
Net Amount, Derivative Liabilities	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	76,000,000	93,000,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	76,000,000	93,000,000
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	94,000,000	114,000,000
Fair value of derivative liabilities	93,000,000	113,000,000
Net Amount, Derivative Assets	76,000,000	93,000,000
Net Amount, Derivative Liabilities	1,000,000	1,000,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		0
Derivative Liability, Fair Value, Gross Liability	94,000,000	114,000,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Interest Rate Swaps [Member] | Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,940,000,000	1,835,000,000
Net Amount, Derivative Liabilities	1,940,000,000	1,835,000,000
Derivative Liability, Fair Value, Gross Liability	1,940,000,000	1,835,000,000
Currency Swaps [Member] | Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	38,000,000	41,000,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	38,000,000	41,000,000
Net Amount, Derivative Assets	$ 38,000,000	41,000,000
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		$ 0