Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rates	(11.00%)	35.00%	(5.00%)	30.00%
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 37.2		$ 37.2			$ 19.7
Reduction in provision for income taxes due to impact of effective tax rate	33.3		33.3
Deferred tax assets classified as other non-current assets	374.0		374.0			$ 227.2
Deferred tax assets, valuation allowance	33.1		33.1
Other Noncurrent Liabilities
Income Tax Contingency [Line Items]
Increase in unrecognized tax benefits is reasonably possible	15.8		15.8
Other Noncurrent Assets
Income Tax Contingency [Line Items]
Unrecognized tax benefits	21.4		21.4
Accounting Standards Update 2016-09
Income Tax Contingency [Line Items]
Increase to deferred tax assets	43.6		43.6
Effective income tax rate reconciliation, share-based compensation, excess tax benefit	$ 41.7		$ 110.5
Retained Earnings | Accounting Standards Update 2016-09
Income Tax Contingency [Line Items]
Cumulative effect adjustment to retained earnings					$ 43.6