CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 25,993	$ 14,933	$ 15,153
Other comprehensive income (loss), before tax:
Changes in unrealized loss on securities available-for-sale	528	(12,059)	(3,365)
Changes in unrealized loss on derivative hedges	(838)	(272)	(1,383)
Changes in unrealized loss on post-retirement plans	(328)	90	27
Income taxes related to other comprehensive income (loss):
Changes in unrealized loss on securities available-for-sale	(114)	4,221	1,177
Changes in unrealized loss on derivative hedges	386	95	484
Changes in unrealized loss on post-retirement plans	138	(30)	(2)
Total other comprehensive loss	(228)	(7,955)	(3,062)
Total comprehensive income	$ 25,765	$ 6,978	$ 12,091