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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ 29	$ 63	$ 108	$ 90
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		3	(7)	7	7
All Other Futures Contracts And Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		21	(9)	34	(17)
Investment And Embedded Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		24	(16)	41	(10)
Guaranteed Minimum Income Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[1]	41	118	79	211
Future contracts on equities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	[2]	(44)	(38)	(22)	(112)
Other Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		8	(1)	10	1
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative		$ 5	$ 79	$ 67	$ 100

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

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