Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for loan and lease losses	$ 10,676	$ 9,577	$ 13,737
Interest income on nonperforming loans	384	417	214
Compensation and benefits	10,885	10,406	14,504
Purchase accounting adjustments	0	0	527
Liabilities held at fair value	12	3	1
Other	2,333	2,515	3,088
Deferred Tax Assets, Net of Valuation Allowance	24,290	22,918	32,071
Total
Prepaid pension	8,700	8,140	11,439
Depreciation	4,193	2,686	3,006
Intangibles	971	776	882
Purchase accounting adjustments	328	194	0
Leases	1,790	1,145	1,687
Other	1,459	774	1,214
Total deferred tax liabilities	17,441	13,715	18,228
Net deferred tax asset at year-end	6,849	9,203	13,843
Net deferred tax asset at beginning of year	9,203	13,843	16,185
Decrease in net deferred tax asset	(2,354)	(4,640)	(2,342)
Purchase accounting adjustments, net	0	0	(483)
Federal tax reform remeasurement of AOCI deferred tax asset	0	9,958	0
Deferred tax expense	$ 2,354	$ 14,598	$ 1,859