Fair Value Measurements and Risk - Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018		Mar. 31, 2017
Gains and losses on derivative instruments
Interest expense and related financing costs	$ 19.3		$ 19.5
Other (income) expense, net	(0.3)		(2.5)
Cash Flow Hedging
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	(5.1)		0.0
Amount of Gain (Loss) Reclassified from OCI into Income	6.3		0.9
Cash Flow Hedging | Interest rate contracts
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	1.5		0.1
Cash Flow Hedging | Interest rate contracts | Interest expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Reclassified from OCI into Income	0.2		0.9
Cash Flow Hedging | Currency contracts
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	(6.6)	[1]	(0.1)
Derivative instruments, Gain (Loss) Recognized in OCI, Amount Excluded from Effectiveness Testing, Net	(0.8)
Cash Flow Hedging | Currency contracts | Other expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Reclassified from OCI into Income	6.1		0.0
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0.9		$ 0.0

[1] (1)Amount of gain (loss) recognized in OCI includes $(0.8) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI.