Long-Lived Assets - Summary of Carrying Value of Acquired Customer Contracts (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 166,289	$ 157,963
Accumulated Amortization	(139,836)	(125,437)
Net Amount	26,453	32,526
Acquired customer contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	153,790	148,872
Accumulated Amortization	(105,778)	(93,767)
Net Amount	$ 48,012	$ 55,105