Long-Lived Assets - Summary of Carrying Value of Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments in client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 37,482	$ 25,176
Accumulated Amortization	(23,265)	(17,060)
Net Amount	14,217	8,116
Capitalized costs
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,831	10,868
Accumulated Amortization	(5,130)	(2,489)
Net Amount	11,701	8,379
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	83,085	91,584
Accumulated Amortization	(68,328)	(68,341)
Net Amount	14,757	23,243
Client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	137,398	127,628
Accumulated Amortization	(96,723)	(87,890)
Net Amount	40,675	39,738
Acquired software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	65,500	66,798
Accumulated Amortization	(62,306)	(61,475)
Net Amount	3,194	5,323
Internal use software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	64,243	63,391
Accumulated Amortization	(37,010)	(33,619)
Net Amount	27,233	29,772
Software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	129,743	130,189
Accumulated Amortization	(99,316)	(95,094)
Net Amount	$ 30,427	$ 35,095