Derivatives and Hedging Activities - Carrying Amount of Hedged Items Currently Designated in a Hedging Relationship and Related Cumulative Hedging Adjustment (Detail) - Accounted for as hedges - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Value	$ 14,768	$ 10,804
Cumulative Hedging Adjustment	(568)	(350)
Deposits
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Value	3,493	6,311
Cumulative Hedging Adjustment	(190)	(280)
Unsecured short-term borrowings
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Value	12,202	7,295
Cumulative Hedging Adjustment	(177)	(47)
Unsecured long-term borrowings
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Value	127,643	151,215
Cumulative Hedging Adjustment	$ (17,025)	$ (15,134)