Intangible Assets and Goodwill (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Intangible Assets and Goodwill
Goodwill	$ 8,965	$ 8,965
Finite-lived intangible asset
Accumulated Amortization	(3,256)	(3,325)
Total Intangible Assets
Cost of total intangible assets	27,596	28,248
Net total intangible assets	24,340	24,923
Amgen Amendment
Finite-lived intangible asset
Estimated Life	16 years
Cost	14,500	14,500
Accumulated Amortization	(2,467)	(2,018)
Net	12,033	12,482
Core Technology
Finite-lived intangible asset
Estimated Life	11 years
Cost	1,296	1,948
Accumulated Amortization	(789)	(1,307)
Net	507	641
IPR&D
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	$ 11,800	$ 11,800