Collaborative and Other Relationships (Details 3) (AbbVie, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
AbbVie
Summary of activity related to collaboration with Facet Biotech
Total expense incurred by collaboration	$ 133.4	$ 128.0	$ 105.2
Biogen Idec's share of expense reflected within our consolidation statements of income	$ 71.0	$ 65.6	$ 54.2