Fair Value Measurements and Risk - Gain (Loss) on Nonderivative Instrument (Details) - Net Investment Hedging - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	$ 1.9	$ (7.8)	$ (4.2)	$ (11.6)
Cross-currency swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	13.3	(6.1)	2.0	(8.6)
Foreign currency denominated debt
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	0.0	(4.9)	(4.4)	(7.2)
Foreign currency denominated deferred intercompany royalties
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	$ 1.9	$ (2.9)	$ 0.2	$ (4.4)