Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 549	$ 958
Less: Related collateral	(73)	155
Total derivative assets	622	803
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	433	782
Foreign Exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	55	62
Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	53	110
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	1	0
Other [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 7	$ 4