Goodwill (Changes in the Net Carrying Amount of Goodwill by Reporting Segment) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Goodwill Roll Forward
Net carrying value, beginning of period:	$ 2,416	$ 2,416
Acquisition activity	0	0
Net carrying value, end of period:	2,416	2,416
Commercial Banking
Goodwill Roll Forward
Net carrying value, beginning of period:	613	613
Acquisition activity	0	0
Net carrying value, end of period:	613	613
Branch Banking
Goodwill Roll Forward
Net carrying value, beginning of period:	1,655	1,655
Acquisition activity	0	0
Net carrying value, end of period:	1,655	1,655
Consumer Lending
Goodwill Roll Forward
Net carrying value, beginning of period:	0	0
Acquisition activity	0	0
Net carrying value, end of period:	0	0
Wealth and Asset Management
Goodwill Roll Forward
Net carrying value, beginning of period:	148	148
Acquisition activity	0	0
Net carrying value, end of period:	$ 148	$ 148