Acquisitions/Dispositions Acquisitions/Dispositions - Schedule of Subsidiary Income Statement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noninterest Expense	$ 5,764	$ 5,468	[1]	$ 5,160	[2]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	2,959	2,830	[1]	2,849	[2]
Premium Assignment Corporation [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	56	60		59
Noninterest Expense	31	27		22
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 25	$ 33		$ 37

[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.