Collaborative and Other Relationships Collaborative and Other Relationships (Tables)

6 Months Ended

Jun. 30, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Revenues from anti-CD20 therapeutic programs

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(In millions)	2018		2017		2018		2017
Biogen's share of pre-tax profits in the U.S. for RITUXAN and GAZYVA	$	359.0	$	347.5	$	708.6	$	671.0
Other revenues from anti-CD20 therapeutic programs	131.4		49.6		225.0		66.7
Total revenues from anti-CD20 therapeutic programs	$	490.4	$	397.1	$	933.6	$	737.7

Summary of Activity Related to Aducanumab Collaboration

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(In millions)	2018		2017		2018		2017
Total development expense incurred by the collaboration related to the advancement of aducanumab	$	76.5	$	74.6	$	140.0	$	128.9
Biogen's share of aducanumab development expense reflected in research and development expense in our condensed consolidated statements of income	$	65.0	$	74.6	$	128.5	$	128.9
Total sales and marketing expense incurred by the collaboration related to the advancement of aducanumab	$	14.0	$	4.8	$	21.2	$	9.8
Biogen's share of aducanumab sales and marketing expense reflected in selling, general and administrative expense our condensed consolidated statements of income	$	9.2	$	4.8	$	13.9	$	9.8

Summary of Activity Related to E2609 and BAN2401 Collaboration

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(In millions)	2018		2017		2018		2017
Total development expense incurred by the collaboration related to the advancement of BAN2401 and E2609	$	54.6	$	29.5	$	111.1	$	66.7
Biogen's share of BAN2401 and E2609 development expense reflected in research and development expense in our condensed consolidated statements of income	$	27.3	$	14.7	$	55.5	$	33.3