Retirement Plans - Schedule of Benefit Obligation, Fair Value of Assets, and Funded Status of the Plans (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States
Change in benefit obligation
Benefit obligation at beginning of year	$ 7,809	$ 16,717
Interest cost	224	648	$ 622
Actuarial loss	813	400
Benefits paid	(398)	(840)
Settlements	0	(9,116)
Benefit obligation at end of year	8,448	7,809	16,717
Change in plan asset
Fair value of assets at beginning of year	4,360	12,468
Actual gain on plan assets	197	1,298
Employer contribution	300	550
Benefits paid	(398)	(840)
Settlements	0	(9,116)
Fair value of assets at end of year	4,459	4,360	12,468
Funded status at end of year	(3,989)	(3,449)
Amount recognized in the consolidated balance sheet consists of:
Other long-term liabilities	(3,989)	(3,449)
Amounts recognized in accumulated other comprehensive income consists of:
Net loss	2,686	1,893
Foreign Plan
Change in benefit obligation
Interest cost			194
United Kingdom
Change in benefit obligation
Benefit obligation at beginning of year	9,101	7,750
Interest cost	184	221
Actuarial loss	996	1,142
Benefits paid	(283)	(326)
Foreign currency exchange rate changes	267	314
Benefit obligation at end of year	10,265	9,101	7,750
Change in plan asset
Fair value of assets at beginning of year	7,290	6,347
Actual gain on plan assets	453	697
Employer contribution	337	314
Benefits paid	(319)	(326)
Foreign currency exchange rate changes	214	258
Fair value of assets at end of year	7,975	7,290	$ 6,347
Funded status at end of year	(2,290)	(1,811)
Amount recognized in the consolidated balance sheet consists of:
Other long-term liabilities	(2,290)	(1,811)
Amounts recognized in accumulated other comprehensive income consists of:
Net loss	2,247	1,641
Prior service cost	152	172
Defined benefit plan, comprehensive (income) loss	$ 2,399	$ 1,813