Inventory (Tables)

12 Months Ended

Dec. 31, 2013

Inventory Disclosure [Abstract]

Components of inventory

	As of December 31,
(In millions)	2013		2012
Raw materials	$	115.0	$	101.8
Work in process	435.4		244.9
Finished goods	108.6		100.7
Total inventory	$	659.0	$	447.4

Components of inventory by product

	As of December 31,
(In millions)	2013		2012
AVONEX	$	176.9	$	144.0
TYSABRI	170.9		114.8
TECFIDERA	33.6		—
Other	162.6		86.8
Total finished goods and work in process	544.0		345.6
Raw materials	115.0		101.8
Total inventory	$	659.0	$	447.4