Defined Benefit Pension Plans - Schedule of Net Periodic Pension Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service cost	$ 4,027	$ 3,711	$ 4,034
Interest cost	1,817	2,278	2,324
Expected return on plan assets	(453)	(608)	(670)
Amortization of prior service costs	68	68	61
Amortization of actuarial net loss	2,255	1,648	1,533
Settlement	286	250	1
Curtailment	0	0	1
Net periodic benefit cost	$ 8,000	$ 7,347	$ 7,284