Pension Plan (Details) - Components of net periodic pension cost - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of net periodic pension cost [Abstract]
Interest cost	$ 117	$ 124	$ 350	$ 365
Expected return on plan assets	(180)	(168)	(539)	(504)
Amortization of net actuarial loss	54	53	163	149
Net periodic pension cost	$ (9)	$ 9	$ (26)	$ 10