Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Other Income (Expense), Net
Interest income	$ 26.0	$ 20.6	$ 81.4	$ 54.2
Interest expense	(49.0)	(61.8)	(151.2)	(188.8)
Gain (loss) on investments, net	141.1	(4.0)	132.0	(15.0)
Foreign exchange gains (losses), net	0.2	6.7	(13.8)	8.4
Other, net	(3.2)	(5.5)	(8.8)	(9.4)
Total other income (expense), net	115.1	$ (44.0)	39.6	$ (150.6)
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	935.8		935.8		$ 761.6
Current portion of contingent consideration obligations	381.5		381.5		844.6
Employee compensation and benefits	274.1		274.1		297.7
Royalties and licensing fees	226.3		226.3		206.7
Construction in progress	196.6		196.6		159.7
Collaboration expenses	101.5		101.5		183.7
Other	640.0		640.0		636.9
Total accrued expenses and other	2,578.5		2,578.5		2,901.3
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	$ 758.5		$ 758.5		$ 572.0