Defined Benefit Plans - Net Periodic Pension Costs (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 260	$ 300
Interest costs	270	300
Expected return on plan assets	(350)	(430)
Amortization of net (gain)/loss	140	250
Net periodic benefit cost	$ 320	$ 420