Long-Lived Assets - Summary of Carrying Values of Contract Cost Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Capitalized Contract Cost [Line Items]
Gross Carrying Amount	$ 63,661
Accumulated Amortization	(25,304)	$ 0
Net Amount	38,357
Client contract incentives
Capitalized Contract Cost [Line Items]
Gross Carrying Amount	26,617
Accumulated Amortization	(12,508)
Net Amount	14,109
Capitalized costs
Capitalized Contract Cost [Line Items]
Gross Carrying Amount	32,099
Accumulated Amortization	(12,440)
Net Amount	19,659
Capitalized commission fees
Capitalized Contract Cost [Line Items]
Gross Carrying Amount	4,945
Accumulated Amortization	(356)
Net Amount	$ 4,589