Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits that would favorably impact the effective tax rate	$ 66,000,000	$ 66,000,000
Estimated change in balance of unrecognized tax benefits, within the next twelve months	53,000,000	53,000,000
Unrecognized tax benefits	80,000,000	80,000,000	$ 77,000,000
Cumulative effect of adopting ASU 2014-01 [Member] | Low Income Housing Tax Credit Investments [Member]
Operating Loss Carryforwards [Line Items]
Amortization recognized for low income housing tax credits associated with adoption of ASU 2014-01	51,000,000	102,000,000
Tax credits recognized for low income housing tax credits associated with adoption of ASU 2014-01	56,000,000	111,000,000
Other tax benefits recognized for low income housing tax credits associated with adoption of ASU 2014-01	18,000,000	$ 37,000,000
National City Acquisition [Member]
Operating Loss Carryforwards [Line Items]
Certain Tax Examination Adjustments Under Review Earliest Year		2004
Certain Tax Examination Adjustments Under Review Latest Year		2008
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net Operating Loss Carryforwards	2,486,000,000	$ 2,486,000,000	2,594,000,000
Tax Credit Carryforward Valuation Allowance	64,000,000	$ 64,000,000
Operating Loss Carryforwards Earliest Expiration Date		2015
Operating Loss Carryforwards Latest Expiration Date		2035
Reduction of state net operating losses	60,000,000	$ 60,000,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Net Operating Loss Carryforwards	$ 947,000,000	$ 947,000,000	$ 997,000,000
Operating Loss Carryforwards Expiration Date		Dec. 31, 2032
Tax Credit Carryforward Expiration Date		Dec. 31, 2032
Income Tax Examination Earliest Year Under Examination		2011
Income Tax Examination Latest Year Under Examination		2013