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, 2019		Sep. 30, 2018	Sep. 30, 2019		Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (223)		$ (17)	$ (562)		$ 91
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(20)		(2)	(57)		5
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(55)		26	(270)		26
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(22)		13	(83)		47
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		0	[1]	0	2	[1]	0
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(97)		37	(408)		78
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(106)		54	(57)		133
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[3]	(6)		(100)	(89)		(122)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(14)		(8)	(8)		2
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (126)		$ (54)	$ (154)		$ 13

[1] Includes embedded derivatives.

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

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