Quarterly report pursuant to Section 13 or 15(d)

Property, Equipment and Software - Additional Information (Details)

v3.8.0.1
Property, Equipment and Software - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Property, Plant and Equipment [Line Items]      
Depreciation and amortization expense for property, equipment and software $ 6.9 $ 6.6  
Carrying amount of capitalized software development costs 77.7   $ 73.4
Accumulated depreciation of capitalized software development costs (30.4)   $ (27.8)
Software      
Property, Plant and Equipment [Line Items]      
Depreciation and amortization expense for property, equipment and software $ 2.6 $ 1.7