Long-Lived Assets - Summary of Carrying Value of Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 308,502	$ 306,835
Accumulated Amortization	(222,528)	(219,204)
Net Amount	85,974	87,631
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	149,195	148,872
Accumulated Amortization	(93,866)	(93,767)
Net Amount	55,329	55,105
Software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	159,307	157,963
Accumulated Amortization	(128,662)	(125,437)
Net Amount	$ 30,645	$ 32,526