Commitments, Contingent Liabilities and Guarantees - Commitments to Extend Credit or Funding (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Guarantor Obligations [Line Items]
Total loan commitments	$ 33,207	$ 28,435
When-issued and to be announced securities commitments	96	117
Commercial letters of credit	100	124
Principal investing commitments	94	123
Liabilities of certain limited partnerships and other commitments	5	115
Total loan and other commitments	33,502	28,914
Commercial and other [Member]
Guarantor Obligations [Line Items]
Total loan commitments	20,804	19,813
Commercial real estate and construction [Member]
Guarantor Obligations [Line Items]
Total loan commitments	1,537	7,366
Home equity [Member]
Guarantor Obligations [Line Items]
Total loan commitments	7,255	1,256
Credit cards [Member]
Guarantor Obligations [Line Items]
Total loan commitments	$ 3,611