Income Taxes - Significant Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for losses on loans	$ 3,444	$ 4,352
Pension obligations	2,402	3,134
Interest on nonaccrual loans	415	525
Unrealized loss on available-for-sale securities	72	86
Amortization of intangible assets	120	219
Deferred rent payable	194	212
Net Operating Losses	2,444	1,340
Charitable contribution carryforward	1,840
Other	162	20
Total gross deferred tax assets	11,093	9,888
Deferred tax liabilities:
Cumulative contribution in excess of net periodic benefit costs, net	3,134	4,313
Depreciation and amortization of premises and equipment	601	426
Deferred loan fees	317	303
Other	18	17
Total gross deferred tax liabilities	4,070	5,059
Valuation allowance	3,114	1,450
Net deferred tax assets	$ 3,909	$ 3,379