Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Loans, principally due to allowance for loan losses	$ 28,999	$ 28,506
Deferred Costs, Leasing, Gross	596	719
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Contingencies	108	1,785
Deferred Discounts, Finance Charges and Interest Included in Receivables	4,552	7,022
Deferred Tax Assets, Unrealized Losses on Trading Securities	2,093	2,728
Employee benefits	9,009	8,256
Other real estate owned write-downs and carrying costs	598	2,536
Deferred gain on sale of subsidiary	0	253
Deferred revenue on contract	1,087	481
Other	126	760
Deferred tax assets	47,168	53,046
Deferred tax liabilities:
Fixed assets, principally differences in bases and depreciation	(5,140)	(569)
Deferred Tax Liabilities, Unrealized Gains on Available For Sale Securities	(2,538)	(1,351)
Investment in joint venture partnership, principally due to differences in depreciation of partnership assets	(1,301)	(1,053)
Prepaid amounts	(1,139)	(1,385)
Government agency stock dividends	(2,442)	(2,407)
Goodwill and core deposit intangibles	(39,886)	(36,732)
Mortgage servicing rights	(4,422)	(4,144)
Other	(65)	(531)
Deferred tax liabilities	(56,933)	(48,172)
Net deferred tax assets (liabilities)		4,874
Deferred Tax Liabilities, Net	(9,765)
Income Taxes Payable, Current	$ 6,275	$ 4,693