Derivatives and Hedging Activities - Fair Value of Credit Derivatives Purchased and Sold (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Credit Derivatives [Line Items]
Purchased	$ (2)	$ (7)
Sold
Credit derivatives, net	(2)	(7)
Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Purchased	(3)	(7)
Sold		1
Credit derivatives, net	(3)	(6)
Traded Credit Default Swap Indices [Member]
Credit Derivatives [Line Items]
Purchased	1
Sold
Credit derivatives, net	1
Other [Member]
Credit Derivatives [Line Items]
Sold		(1)
Credit derivatives, net		$ (1)