Acquisitions (Summary of Total Consideration) (Details) - In Process Research and Development [Member] $ in Millions	May 25, 2018 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Cash paid for acquisition of Wilson Therapeutics outstanding shares	$ 749.3
Transaction costs	15.1
Total consideration	764.4
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Cash And Equivalents	45.1
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Finite-Lived Intangibles	803.7
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Labor And Related Liabilities	(71.4)
Asset Acquisition, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Other	$ (13.0)