Income Taxes - Valuation Allowance (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Valuation allowance
Valuation allowance	$ 158.8	$ 119.0
FTC
Valuation allowance
Valuation allowance	0.0	12.7
Federal
Valuation allowance
Valuation allowance	69.4	27.3
State
Valuation allowance
Valuation allowance	48.9	41.3
Foreign
Valuation allowance
Valuation allowance	$ 40.5	$ 37.7