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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ 4	$ (223)	$ (420)	$ (562)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		0	(20)	53	(57)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		0	(55)	0	(270)
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		9	(22)	(15)	(83)
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	0	0	0	2
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		9	(97)	38	(408)
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	46	(106)	(426)	(57)
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[3]	(52)	(6)	(30)	(89)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		1	(14)	(2)	(8)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (5)	$ (126)	$ (458)	$ (154)

[1] Includes embedded derivatives.

[2] Excludes foreign exchange gains (losses) related to GLB.

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