Commitments, Contingencies, And Guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (547)	$ (80)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		43	(15)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		0	(80)
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(27)	(36)
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	(1)	1
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		15	(130)
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(685)	114
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[3]	125	(63)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(2)	(1)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (562)	$ 50

[1] Includes embedded derivatives.

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

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