Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 1,526	$ 996	$ 1,187
Less: Related collateral	222	377	394
Total derivative assets	1,304	619	793
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	1,406	628	807
Foreign Exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	41	66	48
Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	74	298	328
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	1	4	4
Other [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 4	$ 0	$ 0