Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Taxes [Abstract]
Foreign subsidiaries tax payable period				8 years
U.S. federal corporate tax rate				21.00%		35.00%
Change in tax rate, income tax benefit						$ (89.6)
Benefit relating to the reduction of the ASC 740-30 liability						69.0
Recorded provisional transition tax obligation						$ 63.3
Adjustment of additional tax expense		$ 7.9
Impact of transition tax expense after adjustments		$ 71.3
Income (loss) before income taxes	$ 77.5		$ (190.2)	$ 143.4	$ (198.8)
Provision (benefit) for income taxes	$ 17.2		$ (43.9)	$ 40.7	$ (45.6)
Effective income tax rate	22.20%		23.10%	28.40%	22.90%