Commitments, Contingencies, And Guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ 54	$ (163)	$ (178)	$ (1)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(17)	(247)	(95)	(515)
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		29	49	5	285
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	(3)	0	(2)	(2)
Investment And Embedded Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		9	(198)	(92)	(232)
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	52	54	(80)	240
Other Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(7)	(19)	(6)	(9)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ 45	$ 35	$ (86)	$ 231

[1] Includes embedded derivatives.

[2] Related to MRB book of business.