Long-Lived Assets - Summary of Aggregate Amortization Related to Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments in client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense			$ 7,402
Capitalized costs
Finite Lived Intangible Assets [Line Items]
Total amortization expense			5,141
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense	$ 10,374	$ 7,898	5,406
Total client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense	10,374	7,898	17,949
Acquired software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	2,229	1,801	1,458
Internal use software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	10,641	9,517	7,845
Software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	$ 12,870	$ 11,318	$ 9,303