Changes in the Net Carrying Amount of Goodwill by Reporting Segment (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Goodwill Roll Forward
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
Goodwill Roll Forward
Net carrying value, beginning of period:	613	613	613
Net carrying value, end of period:	613	613	613
Branch Banking
Goodwill Roll Forward
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
Goodwill Roll Forward
Net carrying value, beginning of period:	148	148	148
Net carrying value, end of period:	$ 148	$ 148	$ 148