Summary of Significant Accounting Policies (Effects of Adoption of Topic 606 - Unaudited Consolidated Statements of Operations) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product sales	$ 3,808.6	$ 3,591.8	$ 7,445.7	$ 7,004.1
Royalties and other revenues	110.9	154.0	239.5	314.0
Net income	$ 615.5	$ 240.3	$ 1,166.1	$ 615.3
Net income per share applicable to common shareholders - basic (in usd per share)	$ 0.67	$ 0.27	$ 1.28	$ 0.68
Net income per share applicable to common shareholders - diluted (in usd per share)	$ 0.67	$ 0.26	$ 1.27	$ 0.67
Before Adoption of Topic 606 | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Product sales	$ 3,809.6		$ 7,452.1
Royalties and other revenues	144.9		296.3
Net income	$ 642.5		$ 1,214.9
Net income per share applicable to common shareholders - basic (in usd per share)	$ 0.70		$ 1.33
Net income per share applicable to common shareholders - diluted (in usd per share)	$ 0.70		$ 1.33