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, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	$ 27	$ (284)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	14	(10)
All Other Futures Contracts And Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	(8)	(34)
Convertibles and Bonds with Warrants Attached [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	0	5
Investment And Embedded Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	6	(39)
Guaranteed Minimum Income Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	93	(228)
Single-Stock Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	(74)	(15)
Other Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	2	(2)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative	$ 21	$ (245)