Employee Benefit Plans - Obligation and Funded Status of Defined Benefit Pension Plan and Retirement Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation
Beginning benefit obligation	$ 39,085	$ 33,951
Service cost	622	503	$ 601
Interest cost	1,209	1,388	1,268
Actuarial (gain) loss	3,491	4,769
Benefits paid	(1,603)	(1,526)
Ending benefit obligation	42,804	39,085	33,951
Change in plan assets
Fair value of plan assets at beginning of year	28,443	23,749
Return on assets	2,300	4,347
Employer contribution	1,492	1,873
Benefits paid	(1,603)	(1,526)
Fair value of plan assets at end of year	30,632	28,443	23,749
Funded status (underfunded)	(12,172)	(10,642)
Amounts recognized in the consolidated balance sheet
Current liabilities	605	588
Non-current liabilities	11,567	10,054
Unrecognized loss included in accumulated other comprehensive loss
Unrecognized loss before tax, beginning balance	10,660	9,485
Amortization	(993)	(885)
Liability (gain) loss	3,491	4,769
Asset loss (gain)	(538)	(2,709)
Unrecognized loss before tax, ending balance	12,620	10,660	$ 9,485
Tax impact	(3,003)	(2,544)
Unrecognized loss included in accumulated other comprehensive loss, net of tax	$ 9,617	$ 8,116