Changes in the Net Carrying Amount of Goodwill by Reporting Segment (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Goodwill [Line Items]
Net carrying value, beginning of period:	$ 2,417	$ 2,417	$ 2,417	$ 2,417
Net carrying value, end of period:	2,417	2,417	2,417	2,417
Commercial Banking [Member]
Goodwill [Line Items]
Net carrying value, beginning of period:	613	613	613	613
Net carrying value, end of period:	613	613	613	613
Branch Banking [Member]
Goodwill [Line Items]
Net carrying value, beginning of period:	1,656	1,656	1,656	1,656
Net carrying value, end of period:	1,656	1,656	1,656	1,656
Investment Advisors [Member]
Goodwill [Line Items]
Net carrying value, beginning of period:	148	148	148	148
Net carrying value, end of period:	$ 148	$ 148	$ 148	$ 148