Derivatives and Hedging - Interest Rate Management Risk Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Estimated pretax losses currently included within Accumulated Other Comprehensive Loss that will be reclassified to earnings in next twelve months	$ 14.0		$ 14.0
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivative [Line Items]
Derivative gain (loss)	$ (1.0)	$ (2.0)	$ 0.4	$ (1.0)