Segment Information (Tables)

12 Months Ended

Dec. 31, 2014

Segment Reporting [Abstract]

Revenue by product

	For the Years Ended December 31,
	2014						2013						2012
(In millions)	United States		Rest of World		Total		United States		Rest of World		Total		United States		Rest of World		Total
Multiple Sclerosis (MS):
AVONEX	$	1,956.7	$	1,056.4	$	3,013.1	$	1,902.4	$	1,103.1	$	3,005.5	$	1,793.7	$	1,119.4	$	2,913.1
PLEGRIDY	27.8		16.7		44.5		—		—		—		—		—		—
TECFIDERA	2,426.6		482.6		2,909.2		864.4		11.7		876.1		—		—		—
TYSABRI	1,025.1		934.4		1,959.5		814.2		712.3		1,526.5		383.1		752.8		1,135.9
FAMPYRA	—		80.2		80.2		—		74.0		74.0		—		57.4		57.4
Hemophilia:
ALPROLIX	72.1		3.9		76.0		—		—		—		—		—		—
ELOCTATE	58.4		—		58.4		—		—		—		—		—		—
Other product revenues:
FUMADERM	—		62.5		62.5		—		60.2		60.2		—		59.7		59.7
Total product revenues	$	5,566.7	$	2,636.7	$	8,203.4	$	3,581.0	$	1,961.3	$	5,542.3	$	2,176.8	$	1,989.3	$	4,166.1

Geographic information

December 31, 2014 (In millions)	U.S.		Europe(1)		Germany		Asia		Other		Total
Product revenues from external customers	$	5,566.7	$	1,383.9	$	811.8	$	112.8	$	328.2	$	8,203.4
Revenues from unconsolidated joint business	$	1,117.1	$	7.7	$	—	$	—	$	70.6	$	1,195.4
Other revenues from external customers	$	212.6	$	31.6	$	1.8	$	58.5	$	—	$	304.5
Long-lived assets	$	1,055.5	$	701.9	$	2.5	$	2.6	$	3.2	$	1,765.7
December 31, 2013 (In millions)	U.S.		Europe(1)		Germany		Asia		Other		Total
Product revenues from external customers	$	3,581.0	$	1,170.2	$	417.7	$	93.2	$	280.2	$	5,542.3
Revenues from unconsolidated joint business	$	1,087.3	$	1.6	$	—	$	3.2	$	33.9	$	1,126.0
Other revenues from external customers	$	193.5	$	26.1	$	1.2	$	43.1	$	—	$	263.9
Long-lived assets	$	984.4	$	758.3	$	2.5	$	2.1	$	3.3	$	1,750.7
December 31, 2012 (In millions)	U.S.		Europe(1)		Germany		Asia		Other		Total
Product revenues from external customers	$	2,176.8	$	1,216.2	$	409.2	$	93.2	$	270.7	$	4,166.1
Revenues from unconsolidated joint business	$	1,033.3	$	14.3	$	—	$	27.5	$	62.8	$	1,137.9
Other revenues from external customers	$	170.2	$	27.9	$	1.1	$	13.3	$	—	$	212.5
Long-lived assets	$	996.6	$	738.6	$	1.9	$	2.9	$	2.2	$	1,742.2