Segment Information - Schedule of Long-lived Assets by Geographic Areas (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	$ 127,297	$ 120,051
United States
Segment Reporting Information [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	83,523	84,118
United Kingdom
Segment Reporting Information [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	37,225	28,602
Other foreign countries
Segment Reporting Information [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	6,549	7,331
International
Segment Reporting Information [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	$ 43,774	$ 35,933