Fair Value Measurement (Qualitative Information About Liabilities Measured at Fair Value on Recurring Basis Using Level 3 Inputs) (Details) - Recurring Basis - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Contingent Consideration Payable | Income approach (probability weighted discounted cash flow)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Liabilities	$ 1,179.6
Derivative Financial Instruments, Liabilities
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Cash flow scenario probability weighting	100.00%
Assumed market participant discount rate	14.00%
Minimum | Contingent Consideration Payable
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Cumulative probability of milestones being achieved (in percent)	22.00%
Assumed market participant discount rate	1.80%
Periods in which milestones are expected to be achieved	2018
Forecast quarterly royalties payable on net sales of relevant products	$ 0.2
Maximum | Contingent Consideration Payable
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Cumulative probability of milestones being achieved (in percent)	90.00%
Assumed market participant discount rate	8.70%
Periods in which milestones are expected to be achieved	2040
Forecast quarterly royalties payable on net sales of relevant products	$ 6.5
Fair value
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Joint venture net written option	$ 32.0	$ 40.0