Goodwill and Other Intangible Assets (Goodwill And Other Intangible Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, Gross, beginning balance	$ 1,900,727,000	$ 1,900,727,000	$ 1,899,159,000
Accumulated impairment loss, beginning balance	(113,076,000)	(112,934,000)	(112,934,000)
Goodwill, Total, beginning balance	1,787,651,000	1,787,793,000	1,786,225,000
Net additions			1,568,000
Goodwill, Impairment Loss	0	(142,000)	0
Goodwill, Period Increase (Decrease)		(142,000)	1,568,000
Goodwill, Gross, ending balance	1,900,727,000	1,900,727,000	1,900,727,000
Accumulated impairment loss, ending balance	(113,076,000)	(113,076,000)	(112,934,000)
Goodwill, Total, ending balance	1,787,651,000	1,787,651,000	1,787,793,000
Finite-lived Intangible Assets [Roll Forward]
Other Intangible Assets, Gross, Beginning Balance	113,471,000	113,471,000	113,471,000
Other Intangible Assets, Accumulated Amortization, Beginning Balance	(76,585,000)	(67,963,000)	(56,738,000)
Other Intangible Assets, Net, Beginning Balance	36,886,000	45,508,000	56,733,000
Other intangible assets, Net additions	0	0	0
Other Intangible Assets, Amortization	(6,756,000)	(8,622,000)	(11,225,000)
Other Intangible Assets, Gross, Ending Balance	113,471,000	113,471,000	113,471,000
Finite-Lived Intangible Assets, Period Increase (Decrease)	(6,756,000)	(8,622,000)	(11,225,000)
Other Intangible Assets, Accumulated Amortization, Ending Balance	(83,341,000)	(76,585,000)	(67,963,000)
Other Intangible Assets, Net, Ending Balance	30,130,000	$ 36,886,000	$ 45,508,000
Commercial Bank
Goodwill [Roll Forward]
Goodwill, Total, ending balance	1,033,744,000
Wealth Management
Goodwill [Roll Forward]
Goodwill, Total, ending balance	2,715,000
Retail Bank
Goodwill [Roll Forward]
Goodwill, Total, ending balance	$ 751,192,000