Subsequent Events (Notes)

12 Months Ended

Dec. 31, 2016

Subsequent Events [Abstract]

Subsequent Events

Subsequent Events

On February 1, 2017, we completed the distribution of the issued and outstanding common stock of Bioverativ to Biogen stockholders. For additional information related to the distribution of Bioverativ, please read Note 1, Summary of Significant Accounting Policies, to these consolidated financial statements.

In connection with the distribution, we entered into a separation and distribution agreement and various other agreements (including a transition services agreement, a tax matters agreement, a manufacturing and supply agreement, an employee matters agreement, an intellectual property matters agreement and certain other commercial agreements). These agreements govern the separation and distribution and the relationship between the two companies going forward. They also provide for the performance of services by each company for the benefit of the other for a period of time (including under the manufacturing and supply agreement pursuant to which we will manufacture and supply certain products and materials to Bioverativ).