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 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Property, Plant and Equipment [Line Items]          
Depreciation and amortization expense for property, equipment and software $ 6.9 $ 6.9 $ 21.3 $ 20.4  
Carrying amount of capitalized software development costs 89.0   89.0   $ 73.4
Accumulated depreciation of capitalized software development costs (36.5)   (36.5)   $ (27.8)
Software          
Property, Plant and Equipment [Line Items]          
Depreciation and amortization expense for property, equipment and software $ 3.2 $ 2.2 $ 8.7 $ 5.7