Commitments and Contingencies (Collaborative Arrangements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Out-licensing arrangements
Milestone income recognized	$ 29.7	$ 14.8	$ 21.5
Product sales	3,950.2	3,128.2	2,693.7
In-licensing Arrangement | ActRIIB Class of Molecule
In-licensing arrangements
Upfront payment		45.0
Support costs	10.1	2.7	0
In-licensing Arrangement | ActRIIB Class of Molecule | Meeting Certain Development, Regulatory and Sales Milestones for HGT-4510 in DMD
In-licensing arrangements
Conditional obligation		165.0
In-licensing Arrangement | ActRIIB Class of Molecule | Successful Commercialization of Other Indications and Molecules
In-licensing arrangements
Conditional obligation		288.0
In-licensing Arrangement | Locked Nucleic Acid Drug Platform
In-licensing arrangements
Upfront payment			6.5
Milestones payment	2.5	4.0	0
Support costs	5.3	2.3	0.1
Maximum conditional obligation	70.5
In-licensing Arrangement | Locked Nucleic Acid Drug Platform | Success Milestones in Designing, Developing and Delivering Pre-clinical LNA Oligonucleotides
In-licensing arrangements
Conditional obligation		13.5
Milestones payment			0
Out-licensing Arrangement
Out-licensing arrangements
Milestone payments received	11.5	0	4.0
Milestone income recognized	17.5	8.4	8.8
Product sales	65.2	51.1	29.4
Out-licensing Arrangement | Development Milestone
Out-licensing arrangements
Maximum milestone payment receivable	39.0
Out-licensing Arrangement | Sales Milestone
Out-licensing arrangements
Maximum milestone payment receivable	$ 54.0