Trading Assets and Liabilities and Derivatives(Detail) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	[1]	$ 6,537	$ 6,202
Trading liabilities		1,330	1,227
US Treasury Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		443	267
Trading liabilities		584	485
US Government Agencies Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		532	547
US States and Political Subdivisions Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		40	42
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		565	545
Trading liabilities		4	1
Collateralized Loan Obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		2	3
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		390	509
Trading liabilities		177	279
Commercial Paper [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		312	327
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets		65	45
Derivative Financial Instruments, Assets
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	[2]	1,449	1,307
Loans [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	[3]	2,739	2,610
Derivative Financial Instruments, Liabilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading liabilities	[2]	$ 565	$ 462

[1] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,152 million and $1,316 million at September 30, 2015 and December 31, 2014, respectively

[2] Amounts include the impact of offsetting cash collateral received from and paid to the same derivative counterparties and the impact of netting derivative assets and derivative liabilities when a legally enforceable master netting agreement or similar agreement exists.

[3] Includes loans related to TRS.