Acquisitions/Dispositions Acquisitions/Dispositions - Additional Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015		Dec. 15, 2016
Business Acquisition [Line Items]
Assets		$ 205,962	$ 204,875
Total liabilities		180,808	181,257
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		2,959	2,830	[1]	$ 2,849	[2]
Noninterest Expense		5,764	5,468	[1]	5,160	[2]
Proceeds from Divestiture of Businesses		261	0		0
Gain (Loss) on Disposition of Business		107	0		0
Premium Assignment Corporation [Member]
Business Acquisition [Line Items]
Assets		1,300
Total liabilities		1,200
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		25	33		37
Revenues		56	60		59
Noninterest Expense		31	27		22
Proceeds from Divestiture of Businesses		261
Gain (Loss) on Disposition of Business		107
Pillar Financial [Member]
Business Combinations [Abstract]
Indefinite-lived Intangible Assets Acquired	[3]	13
Business Acquisition [Line Items]
Business Combination, Consideration Transferred			(197)
Wholesale [Member]
Business Acquisition [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		2,189	1,562	[1]	1,681	[2]
Noninterest Expense		$ 1,869	1,676	[1]	$ 1,523	[2]
Commercial Mortgage Servicing Rights [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets							$ 62
Commercial Mortgage Servicing Rights [Member] | Pillar Financial [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			$ 62

[1] Beginning in the second quarter of 2017, the Company realigned its business segment structure from three segments to two segments. Specifically, the Company retained the previous composition of the Wholesale Banking segment and changed the basis of presentation of the Consumer Banking and Private Wealth Management segment and Mortgage Banking segment such that those segments were combined into a single Consumer segment. Accordingly, business segment information presented for the year ended December 31, 2016 has been revised to conform to the new business segment structure and updated internal funds transfer pricing methodology for consistent presentation.

[2] Beginning in the second quarter of 2017, the Company realigned its business segment structure from three segments to two segments. Specifically, the Company retained the previous composition of the Wholesale Banking segment and changed the basis of presentation of the Consumer Banking and Private Wealth Management segment and Mortgage Banking segment such that those segments were combined into a single Consumer segment. Accordingly, business segment information presented for the year ended December 31, 2015 has been revised to conform to the new business segment structure and updated internal funds transfer pricing methodology for consistent presentation.

[3] Does not include $62 million of commercial mortgage servicing rights acquired.