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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (82)	$ 4	$ 141	$ (420)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(15)	0	(37)	53
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		6	9	45	(15)
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	0	0	1	0
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(9)	9	9	38
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(59)	46	252	(426)
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(4)	(52)	(112)	(30)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(10)	1	(8)	(2)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (73)	$ (5)	$ 132	$ (458)

[1] Includes embedded derivatives.

[2] Related to GMDB and GLB book of business.