Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 22,284	$ 21,798	$ 23,169
Defined benefit pension plans:
Net (loss)/gain arising during the year	(1,219)	326	(6,023)
Amortization of defined benefit pension items:
Net actuarial loss	1,912	2,863	1,682
Prior service cost	205	(33)	(9)
Amortization of defined benefit pension items:	1,707	2,896	1,691
Defined benefit pension plan adjustments	(488)	(3,222)	4,332
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1,232	(1,871)	(7,130)
Total other comprehensive income (loss), net of tax	1,232	(1,871)	(7,130)
Comprehensive income	$ 23,516	$ 19,927	$ 16,039