Intangible Assets and Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Intangible Assets and Goodwill
Goodwill	$ 8,965us-gaap_Goodwill	$ 8,965us-gaap_Goodwill
Finite-lived intangible asset
Accumulated Amortization	(6,042)	(5,789)
Total Intangible Assets
Cost of total intangible assets	27,596	27,596
Intangible Assets, Net (Excluding Goodwill)	21,554	21,807
Amgen Amendment
Finite-lived intangible asset
Estimated Life	16 years
Cost	14,500	14,500
Accumulated Amortization	(4,931)	(4,708)
Net	9,569	9,792
Core Technology
Finite-lived intangible asset
Estimated Life	11 years
Cost	1,296	1,296
Accumulated Amortization	(1,111)	(1,081)
Net	185	215
IPR&D
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	$ 11,800	$ 11,800

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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