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License and Collaboration Agreements (Details) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended		9 Months Ended			18 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended			9 Months Ended		1 Months Ended		3 Months Ended
License and Collaboration Agreements (Details) (USD $)	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Nov. 30, 2009 License and Collaboration Agreements Sanofi	Sep. 30, 2012 License and Collaboration Agreements Sanofi	Sep. 30, 2011 License and Collaboration Agreements Sanofi	Sep. 30, 2012 License and Collaboration Agreements Sanofi	Sep. 30, 2011 License and Collaboration Agreements Sanofi	Dec. 31, 2011 License and Collaboration Agreements Sanofi	Dec. 31, 2011 License and Collaboration Agreements Sanofi Phase 2 clinical trials in breast cancer and non-small cell lung cancer	Mar. 31, 2012 License and Collaboration Agreements Sanofi Phase 2 clinical trial in ovarian cancer	May 31, 2011 License and Collaboration Agreements PharmaEngine	Sep. 30, 2012 License and Collaboration Agreements PharmaEngine	Sep. 30, 2011 License and Collaboration Agreements PharmaEngine	Jun. 30, 2011 License and Collaboration Agreements PharmaEngine	Sep. 30, 2012 License and Collaboration Agreements PharmaEngine	Sep. 30, 2011 License and Collaboration Agreements PharmaEngine	May 31, 2011 License and Collaboration Agreements PharmaEngine Development and regulatory milestone	May 31, 2011 License and Collaboration Agreements PharmaEngine Sales milestone	Mar. 31, 2012 License and Collaboration Agreements PharmaEngine Phase 3 clinical trial in pancreatic cancer
License and collaboration agreements
Upfront license fee received					$ 60,000,000
Milestone payments received											20,000,000	5,000,000
Expected development period from the effective date of agreement					12 years
Recognized revenue under collaboration agreements
Upfront payment						1,250,000	1,250,000	3,750,000	3,750,000
Milestone payment						521,000	208,000	2,454,000	625,000
Development services						8,598,000	6,584,000	25,900,000	15,976,000
Manufacturing services and other						935,000	520,000	2,562,000	1,214,000
Total						11,304,000	8,562,000	34,666,000	21,565,000
Accounts receivable and deferred revenue related to collaboration agreement
Accounts receivable, billed						1,562,000		1,562,000		4,478,000
Accounts receivable, unbilled						4,471,000		4,471,000		2,925,000
Deferred revenue						82,522,000		82,522,000		84,466,000
Collaborative arrangement additional information
Upfront license fees paid													10,000,000			10,000,000
Maximum milestone payment obligation																			80,000,000	130,000,000
Milestone payment																					5,000,000
Research and development expenses	$ 30,885,000	$ 23,913,000	$ 91,294,000	$ 73,101,000										$ 300,000	$ 400,000		$ 5,800,000	$ 10,900,000