Long-Lived Assets - Summary of Carrying Value of Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 264,221	$ 267,141
Accumulated Amortization	(200,410)	(196,039)
Net Amount	63,811	71,102
Client contracts
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	130,668	137,398
Accumulated Amortization	(93,871)	(96,723)
Net Amount	36,797	40,675
Software
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	133,553	129,743
Accumulated Amortization	(106,539)	(99,316)
Net Amount	$ 27,014	$ 30,427