Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 5,888.5	$ 4,474.0	$ 2,670.1
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation, amortization and impairments	680.6	1,016.6	1,081.0
Acquired in-process research and development	0.0	112.5	120.0
Share-based compensation	182.3	157.5	128.0
Deferred income taxes	67.1	108.3	91.7
(Gain) loss on fair value remeasurement of contingent consideration	(63.7)	(12.3)	62.7
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax	55.3	0.0	0.0
Other	69.2	(69.1)	162.1
Changes in operating assets and liabilities, net:
Accounts receivable	68.8	(205.2)	(435.6)
Due from anti-CD20 therapeutic programs	(63.3)	5.7	(232.0)
Inventory	(19.2)	(52.1)	(94.5)
Accrued expenses and other current liabilities	240.2	465.5	(227.4)
Income tax assets and liabilities	16.1	321.7	1,303.9
Other liabilities	(43.3)	(135.4)	(79.0)
Net cash flows provided by operating activities	7,078.6	6,187.7	4,551.0
Cash flows from investing activities:
Proceeds from sales and maturities of marketable securities	6,007.0	9,173.7	5,565.9
Purchases of marketable securities	(5,252.6)	(7,694.8)	(5,355.2)
Contingent consideration related to Fumapharm AG acquisition	(300.0)	(1,500.0)	(1,200.0)
Payments to Acquire Businesses, Net of Cash Acquired	(744.4)	0.0	0.0
Proceeds from Sale of Property, Plant, and Equipment	923.7	0.0	0.0
Payments to Acquire in Process Research and Development	0.0	(112.5)	(120.0)
Purchases of property, plant and equipment	(514.5)	(770.6)	(867.4)
Acquisitions of intangible assets	(155.0)	(3.0)	(975.4)
Payments to Acquire Other Investments	0.0	(462.9)	0.0
Payments to increase investment in Samsung Bioepis	0.0	(676.6)	0.0
Proceeds from Sale of Available-for-sale Securities, Equity	479.3	0.0	0.0
Other	27.0	0.4	(11.0)
Net cash flows provided by (used in) investing activities	470.5	(2,046.3)	(2,963.1)
Cash flows from financing activities:
Purchases of treasury stock	(5,868.3)	(4,352.6)	(1,365.4)
Net contribution (distribution) to noncontrolling interests	4.3	(36.4)	(134.1)
Repayments of borrowings	0.0	(3.2)	(560.9)
Net cash contribution to Bioverativ, Inc.	0.0	0.0	(302.7)
Contingent consideration payments	0.0	(58.2)	(3.0)
Other	3.6	(21.6)	(13.9)
Net cash flows used in financing activities	(5,860.4)	(4,472.0)	(2,380.0)
Net increase (decrease) in cash and cash equivalents	1,688.7	(330.6)	(792.1)
Effect of exchange rate changes on cash and cash equivalents	0.4	(18.6)	39.4
Cash and cash equivalents, beginning of the year	1,224.6	1,573.8	2,326.5
Cash and cash equivalents, end of the year	$ 2,913.7	$ 1,224.6	$ 1,573.8