Defined Benefit Plans - Net Periodic Pension Costs (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 330	$ 320
Interest costs	200	240
Expected return on plan assets	(390)	(370)
Amortization of net (gain)/loss	230	220
Net periodic benefit cost	$ 370	$ 410