Segment Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Revenue by product

Revenues by product are summarized as follows:

	For the Years Ended December 31,
	2017						2016						2015
(In millions)	United States		Rest of World		Total		United States		Rest of World		Total		United States		Rest of World		Total
Multiple Sclerosis (MS):
TECFIDERA	$	3,294.0	$	920.0	$	4,214.0	$	3,169.4	$	798.7	$	3,968.1	$	2,908.2	$	730.2	$	3,638.4
AVONEX	1,593.6		557.9		2,151.5		1,675.3		638.2		2,313.5		1,790.2		840.0		2,630.2
PLEGRIDY	295.5		198.8		494.3		305.0		176.7		481.7		227.1		111.4		338.5
TYSABRI	1,113.8		859.3		1,973.1		1,182.9		780.9		1,963.8		1,103.1		783.0		1,886.1
FAMPYRA	—		91.6		91.6		—		84.9		84.9		—		89.7		89.7
ZINBRYTA	—		52.7		52.7		—		7.8		7.8		—		—		—
Spinal Muscular Atrophy:
SPINRAZA	657.0		226.7		883.7		4.6		—		4.6		—		—		—
Hemophilia:
ELOCTATE	42.2		6.2		48.4		445.2		68.0		513.2		308.3		11.4		319.7
ALPROLIX	21.0		5.0		26.0		268.0		65.7		333.7		208.9		25.6		234.5
Other product revenues:
FUMADERM	—		39.6		39.6		—		45.9		45.9		—		51.4		51.4
BENEPALI	—		370.8		370.8		—		100.6		100.6		—		—		—
FLIXABI	—		9.0		9.0		—		0.1		0.1		—		—		—
Total product revenues	$	7,017.1	$	3,337.6	$	10,354.7	$	7,050.4	$	2,767.5	$	9,817.9	$	6,545.8	$	2,642.7	$	9,188.5

Geographic information

The following tables contain certain financial information by geographic area:

December 31, 2017 (In millions)	U.S.		Europe		Asia		Other		Total
Product revenues from external customers	$	7,017.1	$	2,844.8	$	160.1	$	332.7	$	10,354.7
Revenues from anti-CD20 therapeutic programs	$	1,475.6	$	0.6	$	—	$	83.0	$	1,559.2
Other revenues from external customers	$	249.5	$	67.8	$	42.7	$	—	$	360.0
Long-lived assets	$	1,226.9	$	1,948.2	$	5.2	$	2.1	$	3,182.4
December 31, 2016 (In millions)	U.S.		Europe		Asia		Other		Total
Product revenues from external customers	$	7,050.4	$	2,237.2	$	217.3	$	313.0	$	9,817.9
Revenues from anti-CD20 therapeutic programs	$	1,249.5	$	1.9	$	—	$	63.1	$	1,314.5
Other revenues from external customers	$	224.7	$	71.5	$	20.2	$	—	$	316.4
Long-lived assets	$	1,272.3	$	1,221.1	$	7.0	$	1.4	$	2,501.8
December 31, 2015 (In millions)	U.S.		Europe		Asia		Other		Total
Product revenues from external customers	$	6,545.8	$	2,165.7	$	143.7	$	333.3	$	9,188.5
Revenues from anti-CD20 therapeutic programs	$	1,269.8	$	3.5	$	—	$	65.9	$	1,339.2
Other revenues from external customers	$	142.0	$	31.2	$	62.9	$	—	$	236.1
Long-lived assets	$	1,296.5	$	881.7	$	7.7	$	1.7	$	2,187.6