Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service cost	$ 345	$ 261	$ 1,353
Interest cost	497	601	468
Net periodic benefit cost	$ 842	$ 862	$ 1,821