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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	$ 63	$ (206)	$ 90	$ (490)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	(7)	(10)	7	(20)
All Other Futures Contracts And Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	(9)	(37)	(17)	(71)
Convertibles and Bonds with Warrants Attached [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	0	0	0	5
Investment And Embedded Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	(16)	(47)	(10)	(86)
Guaranteed Minimum Income Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	118	(131)	211	(359)
Single-Stock Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	(38)	(28)	(112)	(43)
Other Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	(1)	0	1	(2)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Loss on Derivative	$ 79	$ (159)	$ 100	$ (404)