Pension Plan (Details) - Components of net periodic pension cost - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of net periodic pension cost [Abstract]
Interest cost	$ 117	$ 121	$ 233	$ 241
Expected return on plan assets	(180)	(168)	(359)	(336)
Amortization of net actuarial loss	55	48	109	96
Net periodic pension cost	$ (8)	$ 1	$ (17)	$ 1