Pension Plan (Details) - Components of net periodic pension cost - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Components of net periodic pension cost [Abstract]
Interest cost	$ 114	$ 117	$ 340	$ 350
Expected return on plan assets	(203)	(180)	(609)	(539)
Amortization of net actuarial loss	56	54	168	163
Net periodic pension benefit	$ (33)	$ (9)	$ (101)	$ (26)