Income Taxes Deferred Tax Assetss And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for credit losses	$ 40,554	$ 62,726
Postretirement and defined benefit plans	7,274	12,659
State loss carryforwards	11,855	9,820
Other accrued expenses	7,663	12,017
Other-than-temporary impairment of investments	2,045	5,187
Other accrued expenses	6,977	9,520
Unrealized holding losses on securities available for sale	5,830	12,260
Other	6,742	8,500
Total gross deferred tax assets	88,940	132,689
Deferred Tax Liabilities, Gross [Abstract]
Mortgage servicing rights	8,204	13,369
Direct leasing	21,917	27,663
Acquisition premiums/discounts	6,030	9,167
Premises and equipment	3,099	5,625
Intangible assets	1,155	1,810
Other	10,420	12,530
Total gross deferred tax liabilities	50,825	70,164
Net deferred tax asset, before valuation allowance	38,115	62,525
Valuation allowance	(11,855)	(8,950)
Net deferred tax asset	26,260	53,575
State and local operating loss carryforwards	369,000	$ 391,000
Deferred tax assets other than temporary impairment losses investment securities	$ 2,000