CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 23,828	$ 27,381	$ 16,497
Other comprehensive income:
Change in net unrealized holding gains on available-for-sale securities and I/O strips	417	(1,711)	(3,809)
Deferred income taxes	(175)	719	1,605
Change in net unamortized unrealized gain on securities available-for-sale that were reclassified to securities held-to-maturity	(51)	(116)	(55)
Deferred income taxes	22	49	23
Reclassification adjustment for losses (gains) realized in income	6	(1,099)	(642)
Deferred income taxes	(3)	461	270
Change in unrealized gains on securities and I/O strips, net of deferred income taxes	216	(1,697)	(2,608)
Change in net pension and other benefit plan liability adjustment	(923)	6	(3,036)
Deferred income taxes	388	(3)	1,275
Change in pension and other benefit plan liability, net of deferred income taxes	(535)	3	(1,761)
Other comprehensive loss	(319)	(1,694)	(4,369)
Total comprehensive income	$ 23,509	$ 25,687	$ 12,128