Derivatives and Hedging Activities - Fair Value of Credit Derivatives Purchased and Sold (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Credit Derivatives [Line Items]
Purchased		$ 1
Sold		(1)	$ (1)
Credit derivatives, net			(1)
Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Purchased	$ (2)	(3)	(2)
Credit derivatives, net	(2)	(3)	(2)
Traded Credit Default Swap Indices [Member]
Credit Derivatives [Line Items]
Purchased	2	4	2
Credit derivatives, net	$ 2	4	2
Other [Member]
Credit Derivatives [Line Items]
Sold		(1)	(1)
Credit derivatives, net		$ (1)	$ (1)