Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 4,474.0	$ 2,670.1	$ 3,695.7
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation, amortization and impairments	1,016.6	1,081.0	682.7
Acquired in-process research and development	112.5	120.0	0.0
Share-based compensation	157.5	128.0	154.8
Deferred income taxes	108.3	91.7	(175.0)
(Gain) loss on fair value remeasurement of contingent consideration	(12.3)	62.7	14.8
Other	(69.1)	162.1	89.0
Changes in operating assets and liabilities, net:
Accounts receivable	(205.2)	(435.6)	(241.4)
Due from anti-CD20 therapeutic programs	5.7	(232.0)	13.9
Inventory	(52.1)	(94.5)	(165.6)
Other assets	(119.1)	(76.6)	59.1
Accrued expenses and other current liabilities	465.5	(227.4)	622.3
Income tax assets and liabilities	321.7	1,303.9	(232.6)
Other liabilities	(16.3)	(2.4)	69.5
Net cash flows provided by operating activities	6,187.7	4,551.0	4,587.2
Cash flows from investing activities:
Proceeds from sales and maturities of marketable securities	9,173.7	5,565.9	7,378.9
Purchases of marketable securities	(7,694.8)	(5,355.2)	(7,913.2)
Contingent consideration related to Fumapharm AG acquisition	(1,500.0)	(1,200.0)	(1,200.0)
Payments to Acquire in Process Research and Development	(112.5)	(120.0)	0.0
Purchases of property, plant and equipment	(770.6)	(867.4)	(616.1)
Acquisitions of intangible assets	(3.0)	(975.4)	(111.6)
Payments to Acquire Other Investments	(462.9)	0.0	0.0
Payments to Acquire Equity Method Investments	(676.6)	0.0	0.0
Other	0.4	(11.0)	(22.8)
Net cash flows used in investing activities	(2,046.3)	(2,963.1)	(2,484.8)
Cash flows from financing activities:
Purchases of treasury stock	(4,352.6)	(1,365.4)	(1,000.0)
Payments related to issuance of stock for share-based compensation arrangements, net	(2.1)	(5.3)	(8.5)
Net distribution to noncontrolling interest	(36.4)	(134.1)	0.0
Repayments of borrowings	(3.2)	(560.9)	(2.7)
Net cash contribution to Bioverativ, Inc.	0.0	(302.7)	0.0
Contingent consideration payments	(58.2)	(3.0)	(38.6)
Other	(19.5)	(8.6)	(2.8)
Net cash flows used in financing activities	(4,472.0)	(2,380.0)	(1,052.6)
Net increase (decrease) in cash and cash equivalents	(330.6)	(792.1)	1,049.8
Effect of exchange rate changes on cash and cash equivalents	(18.6)	39.4	(31.3)
Cash and cash equivalents, beginning of the year	1,573.8	2,326.5	1,308.0
Cash and cash equivalents, end of the year	$ 1,224.6	$ 1,573.8	$ 2,326.5