Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flow from operating activities:
Net income	$ 1,727.6	$ 4,060.5	$ 5,888.5
Adjustments to reconcile net income to net cash flow from operating activities:
Depreciation and amortization	487.7	457.2	464.7
Impairment of intangible assets	629.3	209.7	215.9
Excess and obsolescence charges related to inventory	167.6	26.6	52.2
Acquired in-process research and development	18.0	75.0	0.0
Share-based compensation	238.6	198.3	182.3
Changes in fair value	(50.7)	(86.3)	(63.7)
(Gain)/loss on divestiture of Hillerød, Denmark manufacturing operations	0.0	(92.5)	55.3
Deferred income taxes	(426.8)	149.0	67.1
(Gain) loss on strategic investments	826.8	(681.8)	(147.3)
(Gain) loss on equity method investment	(34.9)	(3.3)	77.4
Other	202.2	104.6	86.9
Changes in operating assets and liabilities, net:
Accounts receivable	324.8	2.8	68.8
Due from anti-CD20 therapeutic programs	1.2	176.7	(63.3)
Inventory	(462.4)	(316.3)	(19.2)
Accrued expense and other current liabilities	(95.4)	154.2	240.2
Income tax assets and liabilities	230.8	(67.5)	16.1
Other changes in operating assets and liabilities, net	(144.5)	(137.1)	(43.3)
Net cash flow provided by operating activities	3,639.9	4,229.8	7,078.6
Cash flow from investing activities:
Purchases of property, plant and equipment	(258.1)	(424.8)	(514.5)
Proceeds from sales and maturities of marketable securities	3,405.4	7,299.4	6,007.0
Purchases of marketable securities	(3,808.7)	(6,397.7)	(5,252.6)
Contingent consideration paid related to Fumapharm AG acquisition	0.0	0.0	(300.0)
Acquisition of Nightstar Therapeutics plc, net of cash acquired	0.0	0.0	(744.4)
Proceeds from divestiture of Hillerød, Denmark manufacturing operations	28.1	0.0	923.7
Acquired in-process research and development	(18.0)	(75.0)	0.0
Acquisitions of intangible assets	(18.8)	(52.0)	(155.0)
Proceeds from sales of strategic investments	93.5	74.9	479.3
Other	12.9	(26.9)	27.0
Net cash flow (used in) provided by investing activities	(563.7)	(608.6)	470.5
Cash flow from financing activities:
Purchase of treasury stock	(1,800.0)	(6,679.1)	(5,868.3)
Payments related to issuance of stock for share-based compensation arrangements, net	(0.7)	(4.6)	0.0
Repayments of borrowings and premiums paid on debt exchange	(170.0)	0.0	0.0
Proceeds from borrowings	0.0	2,967.4	0.0
Repayments of borrowings	0.0	(1,500.0)	0.0
Net (distribution) contribution to noncontrolling interest	(94.4)	(71.0)	4.3
Other	(21.1)	14.6	3.6
Net cash flow used in financing activities	(2,086.2)	(5,272.7)	(5,860.4)
Net increase (decrease) in cash and cash equivalents	990.0	(1,651.5)	1,688.7
Effect of exchange rate changes on cash and cash equivalents	(59.8)	69.0	0.4
Cash and cash equivalents, beginning of the year	1,331.2	2,913.7	1,224.6
Cash and cash equivalents, end of the year	2,261.4	1,331.2	2,913.7
Sangamo Therapeutics, Inc. Agreement
Cash flow from investing activities:
Purchase of subsidiaries and affiliates	0.0	(141.8)	0.0
Denali Therapeutics
Cash flow from investing activities:
Purchase of subsidiaries and affiliates	0.0	(423.7)	0.0
Sage Therapeutics
Cash flow from investing activities:
Purchase of subsidiaries and affiliates	$ 0.0	$ (441.0)	$ 0.0