Derivative Instruments - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value		$ 89	$ 67
Derivative, Collateral, Right to Reclaim Cash	$ 36	103
Collateral Already Posted, Aggregate Fair Value		109	$ 84
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,194	1,400
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Swap One [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,176	1,177
Variable Interest Entity, Primary Beneficiary [Member] | Currency Swaps [Member]
Derivative [Line Items]
Derivative, Notional Amount	329	345
Variable Interest Entity, Primary Beneficiary [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative, Notional Amount	9	10
AFS [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	332	493
AFS [Member] | Interest Rate Swap One [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 1,261	$ 1,122