Agreements with Other Companies (Details) (USD $)	12 Months Ended				1 Months Ended	3 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2010	Dec. 31, 2012 Pfizer	Dec. 31, 2012 BTG	Dec. 31, 2009 BTG	Dec. 31, 2008 SBIO Pte Ltd	Mar. 31, 2011 SBIO Pte Ltd	Dec. 31, 2012 SBIO Pte Ltd	Dec. 31, 2011 SBIO Pte Ltd	May 31, 2010 SBIO Pte Ltd	Dec. 31, 2012 SBIO Pte Ltd JAK2 inhibitor license
Agreements with Other Companies
License revenue	$ 59,165,000	$ 1,500,000
Potential milestone payments which the company could receive under the agreement		11,500,000
Royalty percentage of net sales		8.00%
Maximum patent term extension		5 years
Cumulative milestone payments received		3,000,000
Upfront payment				13,000,000
Milestone payment				7,000,000
Potential milestone payments the company could make under the agreement				140,000,000
Potential royalty payments the company could make under the agreement				160,000,000
Development and license agreement expiration period after the first commercial sale			10 years
Upfront payment and equity investment					25,000,000
Additional payment under licensing and collaboration agreement									20,000,000
Amount which company may receive related to ONX 0803 and ONX 0805 or proceeds from acquisition of S*BIO.							14,000,000
Write off of unamortized balance of advance funding payment						12,700,000
Impairment charge							500,000	3,800,000
Cash received from SBIO										$ 4,100,000