Trading Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	$ 6,049		$ 6,279
Trading Liabilities, Fair Value Disclosure	1,161		1,806
US Treasury Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	111		144
Trading Liabilities, Fair Value Disclosure	582		569
US Government Agencies Debt Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	462		478
US States and Political Subdivisions Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	34		54
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	432		412
Collateralized Debt Obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	55		45
Asset-backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	36		37
Corporate And Other Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	567		345
Trading Liabilities, Fair Value Disclosure	173		77
Commercial Paper [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	28		229
Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	100		91
Trading Liabilities, Fair Value Disclosure	9		37
Derivative Financial Instruments, Assets
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	1,905	[1]	2,414	[1]
Loans
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Account Assets, Fair Value Disclosure	2,319	[2]	2,030	[2]
Derivative Financial Instruments, Liabilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Liabilities, Fair Value Disclosure	$ 397	[1]	$ 1,123	[1]

[1] 1 Amounts are offset with cash collateral received from or deposited with counterparties when the contracts are subject to ISDA master netting arrangements.

[2] Amounts are offset with cash collateral received from or deposited with counterparties when the contracts are subject to ISDA master netting arrangements.2 Includes loans related to TRS.