Goodwill (Changes in the Net Carrying Amount of Goodwill by Reporting Segment) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016		Dec. 31, 2015
Goodwill [Line Items]
Goodwill				$ 3,381
Accumulated impairment losses				(965)
Goodwill Roll Forward
Net carrying value, beginning of period:	$ 2,416	$ 2,416
Acquisition activity	7	0
Net carrying value, end of period:	2,423	2,416	[1]
Commercial Banking
Goodwill [Line Items]
Goodwill				1,363
Accumulated impairment losses				(750)
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 [Line Items]
Goodwill				1,655
Accumulated impairment losses				0
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 [Line Items]
Goodwill				215
Accumulated impairment losses				(215)
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 [Line Items]
Goodwill				148
Accumulated impairment losses				$ 0
Goodwill Roll Forward
Net carrying value, beginning of period:	148	148
Acquisition activity	7	0
Net carrying value, end of period:	$ 155	$ 148

[1] Net tax deficiencies of $ 6 were reclassified from capital surplus to applicable income tax expense for the nine months ended September 30, 2016 , related to the early adoption of ASU 2016-09 during the fourth quarter of 2016, with an effective date of January 1, 2016