Long-Lived Assets (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Acquired client contracts
Finite Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	114 months
Estimated total amortization expense 2019	$ 10.4
Estimated total amortization expense 2020	9.5
Estimated total amortization expense 2021	6.8
Estimated total amortization expense 2022	6.5
Estimated total amortization expense 2023	$ 5.5
Software
Finite Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	51 months
Estimated total amortization expense 2019	$ 11.2
Estimated total amortization expense 2020	8.9
Estimated total amortization expense 2021	6.9
Estimated total amortization expense 2022	4.9
Estimated total amortization expense 2023	$ 2.4
Client contract costs
Finite Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	31 months