Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 1,187	$ 1,431
Less: Related collateral	494	486
Total derivative assets	693	945
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	1,114	1,257
Foreign exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	23	64
Energy and Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	47	96
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	3	12
Equity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral		$ 2