Goodwill and Intangbile Assets - Summary of Carrying Value of Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 334,620	$ 320,079
Accumulated Amortization	(257,807)	(245,614)
Net Amount	76,813	74,465
Acquired customer contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	163,433	153,790
Accumulated Amortization	(110,438)	(105,778)
Net Amount	52,995	48,012
Software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	171,187	166,289
Accumulated Amortization	(147,369)	(139,836)
Net Amount	$ 23,818	$ 26,453