Income Taxes Deferred Tax Assetss And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for credit losses	$ 37,906	$ 40,554
Tax credit carryforward	27,615	0
Postretirement and defined benefit plans	5,079	7,274
State loss carryforwards	11,605	11,855
Other accrued expenses	7,064	7,663
Other-than-temporary impairment of investments	1,803	2,045
Other accrued expenses	7,232	6,977
Unrealized holding losses on securities available for sale	12,489	5,830
Other	11,127	6,742
Total gross deferred tax assets	121,920	88,940
Deferred Tax Liabilities, Gross [Abstract]
Mortgage servicing rights	8,560	8,204
Direct leasing	31,466	21,917
Acquisition premiums/discounts	5,294	6,030
Premises and equipment	3,579	3,099
Intangible assets	1,292	1,155
Other	12,178	10,420
Total gross deferred tax liabilities	62,369	50,825
Net deferred tax asset, before valuation allowance	59,551	38,115
Valuation allowance	(11,605)	(11,855)
Net deferred tax asset	47,946	26,260
State and local operating loss carryforwards	347,000	$ 369,000
Deferred tax assets other than temporary impairment losses investment securities	$ 1,700