Derivatives and Hedging Activities - Fair Value of Credit Derivatives Purchased and Sold (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Credit Derivatives [Line Items]
Purchased	$ (1)	$ (2)	$ (8)
Sold	(1)
Credit derivatives, net	(2)	(2)	(8)
Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Purchased	(3)	(3)	(6)
Credit derivatives, net	(3)	(3)	(6)
Traded Credit Default Swap Indices [Member]
Credit Derivatives [Line Items]
Purchased	1	1	(2)
Credit derivatives, net	1	1	(2)
Other [Member]
Credit Derivatives [Line Items]
Purchased	1
Sold	$ (1)