Collaborative and Other Relationships (Details 2)	12 Months Ended
	Dec. 31, 2016
Sobi rate to Biogen on net sales in the Sobi Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Reimbursement, under the amended agreement, Method	Royalty
Base rate following first commercial sale in the territory	12.00%
Rate during the reimbursement period	Base Rate plus 5%	[1]
Biogen rate to sobi on net sales in the Biogen North America Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Reimbursement, under the amended agreement, Method	Royalty
Rate during the reimbursement period	Base Rate less 5%	[1]
Biogen rate to sobi on net sales in the Biogen North America Territory [Member] | Sobi Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Base rate following first commercial sale in the territory	12.00%
Biogen rate to sobi on net sales in the Biogen direct Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Reimbursement, under the amended agreement, Method	Royalty
Rate during the reimbursement period	Base Rate less 5%	[1]
Biogen rate to sobi on net sales in the Biogen direct Territory [Member] | Sobi Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Base rate following first commercial sale in the territory	17.00%
Biogen rate to Sobi on net revenue from the Biogen distributor Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Reimbursement, under the amended agreement, Method	Net Revenue Share	[2],[3]
Rate during the reimbursement period	Base Rate less 15%	[1],[2],[3]
Biogen rate to Sobi on net revenue from the Biogen distributor Territory [Member] | Sobi Territory [Member]
Mechanism for reimbursement, under the amended agreement amounts payable
Base rate following first commercial sale in the territory	50.00%	[1],[2],[3]

[1] A credit will be issued to Sobi against its reimbursement of the Opt-in Consideration for each product in an amount equal to the difference in the rate paid by Biogen to Sobi on sales in the Biogen territories for certain periods prior to the first commercial sale in the Sobi Territory versus the rate that otherwise would have been payable on such sales.

[2] Net revenue represents Biogen’s pre-tax receipts from third-party distributors, less expenses incurred by Biogen in the conduct of commercialization activities supporting the distributor activities.

[3] The Biogen Distributor Territory represents Biogen territories where sales are derived utilizing a third-party distributor.