Pension - Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Components of net periodic benefit cost:
Service cost	$ 9	$ 9
Interest cost	9	10
Expected return on plan assets	(14)	(17)
Amortization of actuarial loss	22	22
Total non-service cost	17	15
Net periodic pension cost	$ 26	$ 24