Pension Liability - Net periodic pension expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Liability
Service cost	$ 124		$ 124
Interest cost	274	$ 205	668	$ 637
Expected return on plan assets	(160)	(151)	(496)	(470)
Amortization of actuarial gains and losses	90	64	323	333
Net periodic pension cost	$ 328	$ 118	$ 619	$ 500