Income Taxes - Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Allowance for loan losses	$ 7,985	$ 7,317
Capitalized leases	0	13
Deferred compensation	3,498	3,426
Accrued salaries	738	737
Postretirement benefits	376	375
Equity awards	2,164	3,045
Unrealized actuarial losses on post-retirement benefits	(21)	18
Straight-line rent	1,277	1,051
Asset retirement obligation	70	67
Reserve for accrued interest receivable	578	602
Reserve for loan commitments	216	146
Employee Stock Ownership Plan	615	551
Other	244	261
Depreciation	2,414	2,383
Fair value adjustments of acquired loans	3,713	3,934
Fair value adjustments of pension benefit obligations	160	154
Unrealized losses on debt securities available-for-sale	0	3,575
Total gross deferred tax assets	24,027	27,655
Deferred tax liabilities:
Unrealized gains on debt securities available for sale	1,786	0
Fair value adjustments of acquired securities	20	28
Fair value adjustments of deposit liabilities	219	285
Deferred loan fees	2,224	1,984
Other	30	33
Total gross deferred tax liabilities	4,279	2,330
Net deferred tax asset	$ 19,748	$ 25,325