Employee Benefit Plans - Net periodic benefit costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 275	$ 257
Interest cost	2,269	3,035
Recognized actuarial loss	2,959	2,100
Expected return on plan assets	(7,266)	(7,405)
Prior service cost	72	56
Net periodic benefit cost	$ (1,691)	$ (1,957)