Goodwill And Intangible Assets (Summary Of Intangible Assets Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning Balance	$ 140.7	$ 166.1
Additions		1.8
Amortization	(25.3)	(27.2)
Other	(2.4)
Intangible Assets, Ending Balance	113.0	140.7
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning Balance	16.8	20.7
Additions		0.0
Amortization	(3.5)	(3.9)
Other	0.0
Intangible Assets, Ending Balance	13.3	16.8
Core deposit intangibles
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning Balance	100.9	118.8
Additions		0.0
Amortization	(18.2)	(17.9)
Other	0.0
Intangible Assets, Ending Balance	82.7	100.9
Trade names
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning Balance	21.3	24.4
Additions		0.0
Amortization	(2.8)	(3.1)
Other	(1.5)
Intangible Assets, Ending Balance	17.0	21.3
Other
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning Balance	1.7	2.2
Additions		1.8
Amortization	(0.8)	(2.3)
Other	(0.9)
Intangible Assets, Ending Balance	$ 0.0	$ 1.7