Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Other Income (Expense), Net
Interest income	$ 30.5	$ 26.0	$ 90.8	$ 81.4
Interest expense	(45.8)	(49.0)	(141.4)	(151.2)
Gain (loss) on investments, net	(4.1)	141.1	198.9	132.0
Foreign exchange gains (losses), net	(4.2)	0.2	(4.7)	(13.8)
Other, net	(3.7)	(3.2)	(11.0)	(8.8)
Total other income (expense), net	(27.3)	115.1	132.6	39.6
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net gains (losses) recognized during the period on equity securities	(4.6)	141.2	197.3	139.7
Less: Net gains (losses) recognized during the period on equity securities sold during the period	4.4	0.0	46.8	(0.5)
Unrealized gains (losses) recognized during the period on equity securities held as of September 30, 2019	(9.0)	$ 141.2	150.5	$ 140.2
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	1,085.8		1,085.8		$ 1,051.3
Collaboration expenses	259.5		259.5		320.9
Royalties and licensing fees	222.3		222.3		224.7
Collaboration expenses	188.7		188.7		261.6
Current portion of contingent consideration obligations	147.5		147.5		444.8
Construction in progress	49.5		49.5		125.2
Other	677.4		677.4		609.3
Total accrued expenses and other	2,429.1		2,429.1		2,861.2
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	$ 884.2		$ 884.2		$ 874.7