Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets
Allowance for loan losses	$ 6,992	$ 12,578
Accrued employee benefits	2,569	3,826
Investments	1,560	2,884
Bank premises and equipment	0	349
Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross	555	0
Other	116	1,190
Gross deferred tax assets	11,792	20,827
Valuation allowance	805	1,341
Total deferred tax assets	10,987	19,486
Deferred Tax Liabilities
Purchase accounting adjustments	6,092	10,845
Deferred loan income	2,459	3,181
Derivative instruments	300	0
Bank premises and equipment	307	0
Available-for-sale investment securities	0	312
Other	484	1,305
Total deferred tax liabilities	9,642	15,643
Net deferred tax asset	1,345	$ 3,843
Partnership investment
Deferred Tax Assets
Gross deferred tax assets	$ 3,800