Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 1,187	$ 1,127	$ 643
Less: Related collateral	394	518	230
Total derivative assets	793	609	413
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	807	607	556
Foreign Exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	48	41	39
Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	328	478	47
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 4	$ 1	$ 1