Derivatives and Hedging - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Estimated pretax losses currently included within Accumulated Other Comprehensive Loss that will be reclassified to earnings in next twelve months	$ 9.0
Income (loss) on financial instruments	2.0	$ (14.0)	$ (24.0)
Gain (loss) recognized in income on ineffective portion of derivatives	$ 0.0	0.0	0.0
Not Designated as Hedging Instrument
Derivative [Line Items]
Maximum length of time hedged in foreign currency undesignated hedge (in years)	1 year
Gross Foreign exchange contracts | Not Designated as Hedging Instrument
Derivative [Line Items]
Income (loss) on financial instruments	$ 7.0	$ 0.2	$ 8.0
Cash Flow Hedging
Derivative [Line Items]
Foreign currency exposures, maximum average hedging period ( in years)	2 years