Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Intangible Assets and Goodwill
Goodwill	$ 8,965	$ 8,965
Finite-lived intangible asset
Accumulated Amortization	(6,296)	(5,789)
Total Intangible Assets
Cost of total intangible assets	27,596	27,596
Intangible Assets, Net (Excluding Goodwill)	$ 21,300	21,807
Amgen Amendment
Finite-lived intangible asset
Estimated Life	16 years
Cost	$ 14,500	14,500
Accumulated Amortization	(5,156)	(4,708)
Net	$ 9,344	9,792
Core Technology
Finite-lived intangible asset
Estimated Life	11 years
Cost	$ 1,296	1,296
Accumulated Amortization	(1,140)	(1,081)
Net	156	215
IPR&D
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	$ 11,800	$ 11,800