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, 2019		Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (259)		$ 29	$ (339)		$ 108
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(22)		3	(37)		7
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(135)		0	(215)		0
All Other Futures Contracts, Options and equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(25)		21	(61)		34
Convertible securities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		1	[1]	0	2	[1]	0
Total investment and embedded derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		(181)		24	(311)		41
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(65)		41	49		79
Futures contracts on equities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[3]	(20)		(44)	(83)		(22)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		7		8	6		10
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ (78)		$ 5	$ (28)		$ 67

[1] Includes embedded derivatives.

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

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