Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Other Income (Expense), Net
Interest income	$ 24.4	$ 31.2
Interest expense	(44.3)	(47.9)
Gain (loss) on investments, net	(77.3)	376.4
Foreign exchange gains (losses), net	(18.9)	(2.2)
Other, net	(4.4)	(0.2)
Total other income (expense), net	(120.5)	357.3
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net gains (losses) recognized during the period on equity securities	(60.9)	375.3
Less: Net gains (losses) recognized during the period on equity securities sold during the period	0.0	0.8
Unrealized gains (losses) recognized during the period on equity securities held as of March 31	(60.9)	$ 376.1
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	1,281.8		$ 1,198.9
Collaboration expenses	190.3		309.1
Royalties and licensing fees	209.9		220.9
Collaboration expenses	154.6		281.6
Current portion of contingent consideration obligations	147.3		148.4
Construction in progress	27.3		78.0
Other	662.0		726.7
Total accrued expenses and other	2,437.8		2,765.8
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related reserves for discounts and allowances	$ 1,046.4		$ 1,001.1