Revenue (Summary of Revenue Recognized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 24,539.8	$ 22,319.5	$ 21,493.3
Net product revenue
Disaggregation of Revenue [Line Items]
Revenue	22,694.8	20,377.3	19,866.4
Collaboration and other revenue
Disaggregation of Revenue [Line Items]
Revenue	1,845.0	1,942.2	1,626.9
Collaboration and other revenue associated with prior period transfers of intellectual property
Disaggregation of Revenue [Line Items]
Revenue	$ 135.6	$ 301.5	$ 303.2