Commitments, Contingencies, And Guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (160)	$ 123	$ 223	$ (424)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(6)	10	(22)	53
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(86)	3	39	(24)
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	1	1	1	0
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(91)	14	18	29
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(8)	213	311	(472)
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(64)	(103)	(108)	22
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		3	(1)	2	(3)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (69)	$ 109	$ 205	$ (453)

[1] Includes embedded derivatives.

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