Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 238.7	$ 204.5
Less -- accumulated depreciation	165.0	125.4
Total	73.7	79.1
Computer hardware and software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	180.2	159.4
Furniture, fixtures and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	26.8	22.2
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	24.7	19.2
Work-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 7.0	$ 3.7