Inventory (Tables)

12 Months Ended

Dec. 31, 2012

Inventory Disclosure [Abstract]

Components of inventories

	As of December 31,
(In millions)	2012		2011
Raw materials	$	101.8	$	83.8
Work in process	230.5		169.4
Finished goods	115.1		73.6
Total inventory	$	447.4	$	326.8

Components of inventory by product

	As of December 31,
(In millions)	2012		2011
AVONEX	$	144.0	$	113.3
TYSABRI	114.8		114.7
Other	86.8		15.0
Total finished goods and work in process	345.6		243.0
Raw materials	101.8		83.8
Total inventory	$	447.4	$	326.8