Schedule of Net Periodic Pension Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan [Abstract]
Service cost	$ 1,079	$ 1,049
Interest cost	582	609
Expected return on plan assets	(156)	(181)
Amortization of actuarial net loss	345	403
Amortization of unrecognized prior service costs	17	17
Net periodic benefit cost	$ 1,867	$ 1,897