Fair Value (Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis) (Details) - Non-Recurring [Member] - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		$ 51.8
Assets held for sale	$ 123.6	201.6
Other real estate owned	17.7	22.5
Impaired loans	100.7	151.9
Total	242.0	427.8
Goodwill, Total (Losses)		(354.2)
Assets held for sale, Total (Losses)	(1.9)	(14.7)
Other real estate owned, Total (Losses)	(1.3)	(3.2)
Impaired loans, Total (Losses)	(23.5)	(26.8)
Total (Losses)	(26.7)	(398.9)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		0.0
Assets held for sale	0.0	0.0
Other real estate owned	0.0	0.0
Impaired loans	0.0	0.0
Total	0.0	0.0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		0.0
Assets held for sale	0.0	0.0
Other real estate owned	0.0	0.0
Impaired loans	0.0	0.0
Total	0.0	0.0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		51.8
Assets held for sale	123.6	201.6
Other real estate owned	17.7	22.5
Impaired loans	100.7	151.9
Total	$ 242.0	$ 427.8