Acquisitions/Dispositions Acquisitions/Dispositions-Additional Detail (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Acquisitions and Disposals [Line Items]
Proceeds from Divestiture of Businesses	$ 0	$ 193	$ 0
Gain (Loss) on Disposition of Business	0	105	0
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	2,849	2,420	1,810
Noninterest Expense	5,160	5,543	5,831
Corporate Other [Member]
Significant Acquisitions and Disposals [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	234	425	457
Noninterest Expense	$ 15	92	100
Ridgeworth Capital Management [Member] | Corporate Other [Member]
Significant Acquisitions and Disposals [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest		22	64
Revenues		81	194
Noninterest Expense		59	$ 130
Ridgeworth Capital Management [Member]
Significant Acquisitions and Disposals [Line Items]
Assets under Management, Carrying Amount		49,100
Net Assets		96
Stockholders' Equity Attributable to Noncontrolling Interest		$ 23