Revenue (Summary of Revenue Recognized) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 6,114.0	$ 5,476.6	$ 5,636.7	$ 5,092.2	$ 5,637.6	$ 5,306.9	$ 5,585.0	$ 4,963.8	$ 22,319.5	$ 21,493.3	$ 19,973.8
Net product revenue
Disaggregation of Revenue [Line Items]
Revenue									20,377.3	19,866.4	18,776.5
Collaboration and other revenue
Disaggregation of Revenue [Line Items]
Revenue									1,942.2	1,626.9	1,197.3
Collaboration and other revenue associated with prior period transfers of intellectual property
Disaggregation of Revenue [Line Items]
Revenue									$ 301.5	$ 303.2	$ 144.9