Long-Lived Assets - Summary of Carrying Value of Acquired Client Contracts (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 157,963	$ 155,781
Accumulated Amortization	(125,437)	(119,381)
Net Amount	32,526	36,400
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	148,872	148,148
Accumulated Amortization	(93,767)	(82,692)
Net Amount	$ 55,105	$ 65,456