Shareholders’ Equity and Earnings Per Common Share - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shareholders’ Equity, Other Comprehensive Income and Earnings Per Share
Deferred taxes included in AOCI	$ 491	$ 535	$ 620
Net unrealized gains on securities	638	1,386	3,491
Net unrecognized loss on cash flow hedges	124	(34)	(107)
Net unrecognized losses on defined benefit plan	(2,649)	(2,336)	(2,213)
Total accumulated other comprehensive (loss) income	$ (1,887)	$ (984)	$ 1,171