Fair Value Measurement- Significant Unobservable Inputs (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013			$ 271
Transfers out of Level 3			(5)
Included in earnings (or changes in net assets)			(14)
Purchases			3
Sales			(46)
Fair value at March 31, 2014			209
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period			(13)
Fair value measurements for liabilities using significant unobservable inputs
Fair value at Dec. 31, 2013	75		224
Transfers out of Level 3	(37)
Included in earnings (or changes in net liabilities)	3		(56)
Settlements			2
Fair value at March 31, 2014	41		170
Change in unrealized (gains) or losses for the period included in earnings (or changes in net assets) for liabilities held at the end of the reporting period	3		(27)
Debt and equity instruments
Fair value measurements for assets using significant unobservable inputs
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period	0
Derivative assets
Fair value measurements for assets using significant unobservable inputs
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period	(2)	[1]
Other Assets
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013	105		120
Transfers out of Level 3	0		0
Included in earnings (or changes in net assets)	2	[2]	(5)	[2]
Purchases	8		3
Sales	(5)		(6)
Fair value at March 31, 2014	110		112
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period	0		(2)
Total Assets
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013	139
Transfers out of Level 3	(1)
Included in earnings (or changes in net assets)	0
Purchases	8
Sales	(5)
Fair value at March 31, 2014	141
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period	(2)
Securities available-for-sale | State and political subdivisions
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013	11		45
Transfers out of Level 3	0		0
Included in earnings (or changes in net assets)	0	[3]	(1)	[3]
Purchases	0
Sales	0
Fair value at March 31, 2014	11		44
Trading Assets | Debt and equity instruments
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013	1		48
Transfers out of Level 3	0		0
Included in earnings (or changes in net assets)	0	[4]	3	[4]
Purchases	0		0
Sales	0		(40)
Fair value at March 31, 2014	1		11
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period			0
Trading Assets | Derivative assets
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013	22	[1]	58	[1]
Transfers out of Level 3	(1)	[1]	(5)	[1]
Included in earnings (or changes in net assets)	(2)	[1],[4]	(11)	[1],[4]
Purchases	0	[1]	0	[1]
Sales	0	[1]	0	[1]
Fair value at March 31, 2014	19	[1]	42	[1]
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period			(11)	[1]
Trading Liabilities | Derivative liabilities
Fair value measurements for liabilities using significant unobservable inputs
Fair value at Dec. 31, 2013	75	[5]	224	[5]
Transfers out of Level 3	(37)	[5]
Included in earnings (or changes in net liabilities)	3	[4],[5]	(56)	[4],[5]
Settlements			2	[4],[5]
Fair value at March 31, 2014	41	[5]	170	[5]
Change in unrealized (gains) or losses for the period included in earnings (or changes in net assets) for liabilities held at the end of the reporting period	3	[5]	(27)	[5]
Investment Management funds
Fair value measurements for assets using significant unobservable inputs
Fair value at Dec. 31, 2013			44
Transfers out of Level 3			0
Included in earnings (or changes in net assets)			0	[6]
Purchases			0
Sales			0
Fair value at March 31, 2014			44
Change in unrealized gains or (losses) for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period			$ 0

[1] Derivative assets are reported on a gross basis.

[2] Reported in investment and other income.

[3] Realized gains (losses) are reported in securities gains (losses). Unrealized gains (losses) are reported in accumulated other comprehensive income (loss) except for the credit portion of OTTI losses which are recorded in securities gains (losses).

[4] Reported in foreign exchange and other trading revenue.

[5] Derivative liabilities are reported on a gross basis.

[6] Reported in income from consolidated investment management funds.