Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Total revenues	$ 3,534.3	$ 3,489.8
Cost and expenses:
Cost of sales, excluding amortization and impairment of acquired intangible assets	454.3	602.0
Research and development	476.3	563.7
Selling, general and administrative	570.1	567.7
Amortization and impairment of acquired intangible assets	71.5	68.2
Collaboration profit (loss) sharing	71.8	58.1
Loss on divestiture of Hillerød, Denmark manufacturing operations	0.0
(Gain) loss on fair value remeasurement of contingent consideration	(4.6)	11.5
Restructuring charges	0.0	0.4
Acquired in-process research and development	75.0	0.0
Total cost and expenses	1,714.4	1,987.1
Income from operations	1,819.9	1,502.7
Other income (expense), net	(120.5)	357.3
Income before income tax expense and equity in loss of investee, net of tax	1,699.4	1,860.0
Income tax expense	292.0	422.5
Equity in loss of investee, net of tax	14.8	28.7
Net income	1,392.6	1,408.8
Net income (loss) attributable to noncontrolling interests, net of tax	(6.5)	0.0
Net income attributable to Biogen Inc.	$ 1,399.1	$ 1,408.8
Net income per share:
Basic earnings per share attributable to Biogen Inc.	$ 8.10	$ 7.17
Diluted earnings per share attributable to Biogen Inc.	$ 8.08	$ 7.15
Weighted-average shares used in calculating:
Basic earnings per share attributable to Biogen Inc.	172.8	196.6
Diluted earnings per share attributable to Biogen Inc.	173.1	197.0
Product, net
Total revenues	$ 2,904.6	$ 2,680.0
Revenues from anti-CD20 therapeutic programs
Total revenues	520.4	517.4
Other
Total revenues	$ 109.3	$ 292.4