Defined Benefit Plans - Net Periodic Pension Costs (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 310	$ 260	$ 630	$ 520
Interest costs	230	270	470	540
Expected return on plan assets	(360)	(350)	(730)	(700)
Amortization of net (gain)/loss	230	150	450	290
Net periodic benefit cost	$ 410	$ 330	$ 820	$ 650