Pension - Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of net periodic benefit cost:
Service cost	$ 9	$ 7	$ 27	$ 25
Interest cost	9	10	27	30
Expected return on plan assets	(14)	(17)	(43)	(51)
Amortization of actuarial loss	22	21	64	65
Total non-service cost	17	14	48	44
Net periodic pension cost	$ 26	$ 21	$ 75	$ 69