Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 802	$ 1,187	$ 1,274
Less: Related collateral	327	494	503
Total derivative assets	475	693	771
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	708	1,114	1,195
Foreign Exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	28	23	24
Energy and Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	65	47	51
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 1	$ 3	$ 4