Commitments and Contingences (Details) (Fumapharm AG, USD $)	12 Months Ended	3 Months Ended
	Dec. 31, 2006	Mar. 31, 2015	Jun. 30, 2013
Business Acquisition, Contingent Consideration [Line Items]
Cash portion of consideration	$ 220,000,000
TECFIDERA
Business Acquisition, Contingent Consideration [Line Items]
Maximum contingent consideration in the form of development and approval milestones			15,000,000
Four billion
Business Acquisition, Contingent Consideration [Line Items]
Cash portion of consideration		250,000,000
Cumulative sales level		4,000,000,000
Each additional one billion up to twenty billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level		20,000,000,000
Payment of contingent payment for acquisition		300,000,000
One billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level		1,000,000,000
Three billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level		$ 3,000,000,000