Changes in the Net Carrying Amount of Goodwill by Reporting Segment (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
GoodwillRollForward
Net carrying value, beginning of period:	$ 2,416	$ 2,416	$ 2,416
Net carrying value, end of period:	2,416	2,416	2,416
Commercial Banking
GoodwillRollForward
Net carrying value, beginning of period:	613	613	613
Net carrying value, end of period:	613	613	613
Branch Banking
GoodwillRollForward
Net carrying value, beginning of period:	1,655	1,655	1,655
Net carrying value, end of period:	1,655	1,655	1,655
Investment Advisors
GoodwillRollForward
Net carrying value, beginning of period:	148	148	148
Net carrying value, end of period:	$ 148	$ 148	$ 148