Quarterly report pursuant to Section 13 or 15(d)

Property, Equipment and Software - Additional Information (Details)

v3.10.0.1
Property, Equipment and Software - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Property, Plant and Equipment [Line Items]          
Depreciation and amortization expense for property, equipment and software $ 7.5 $ 6.9 $ 14.4 $ 13.5  
Carrying amount of capitalized software development costs 83.2   83.2   $ 73.4
Accumulated depreciation of capitalized software development costs (33.4)   (33.4)   $ (27.8)
Software          
Property, Plant and Equipment [Line Items]          
Depreciation and amortization expense for property, equipment and software $ 3.0 $ 1.8 $ 5.5 $ 3.4