Long-Lived Assets (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Client contracts
Finite Lived Intangible Assets [Line Items]
Estimated useful life	31 months
Estimated total amortization expense 2018	$ 22.4
Estimated total amortization expense 2019	14.1
Estimated total amortization expense 2020	4.4
Estimated total amortization expense 2021	1.1
Estimated total amortization expense 2022	$ 0.8
Software
Finite Lived Intangible Assets [Line Items]
Estimated useful life	53 months
Estimated total amortization expense 2018	$ 8.3
Estimated total amortization expense 2019	6.3
Estimated total amortization expense 2020	4.7
Estimated total amortization expense 2021	3.3
Estimated total amortization expense 2022	$ 2.6