Long-Lived Assets - Summary of Aggregate Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments in client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense	$ 6,591	$ 5,165	$ 6,409
Capitalized costs
Finite Lived Intangible Assets [Line Items]
Total amortization expense	2,755	1,334	1,007
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense	6,683	8,902	11,951
Client contracts
Finite Lived Intangible Assets [Line Items]
Total amortization expense	16,029	15,401	19,367
Acquired software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	1,806	3,081	3,457
Internal use software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	7,510	8,048	8,404
Software
Finite Lived Intangible Assets [Line Items]
Total amortization expense	$ 9,316	$ 11,129	$ 11,861