Derivatives and Hedging Activities - Credit Derivatives Sold and Held (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Credit Derivatives [Line Items]
Notional Amount	$ 68	$ 101	$ 68
Average Term (Years)
Payment / Performance Risk
Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Notional Amount	55	82	55
Average Term (Years)	6 months 7 days	1 year 2 months 23 days	9 months 7 days
Payment / Performance Risk	22.28%	7.89%	22.28%
Other [Member]
Credit Derivatives [Line Items]
Notional Amount	$ 13	$ 19	$ 13
Average Term (Years)	4 years 9 months 18 days	5 years 4 months 17 days	5 years 11 days
Payment / Performance Risk	8.23%	10.09%	8.82%