Collaborative and Other Research and Development Contracts (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended			6 Months Ended	1 Months Ended		3 Months Ended	1 Months Ended
	Feb. 28, 2011 U.S. Department of Health and Human Services [Member]	Sep. 30, 2009 U.S. Department of Health and Human Services [Member]	Jan. 31, 2007 U.S. Department of Health and Human Services [Member]	Jun. 30, 2012 U.S. Department of Health and Human Services [Member]	Jun. 30, 2006 Green Cross Corporation [Member]	Feb. 28, 2006 Mundipharma International Holdings Limited [Member]	Mar. 31, 2012 Mundipharma International Holdings Limited [Member]	May 31, 2010 AECOM and IRL [Member]	Jun. 30, 2000 AECOM and IRL [Member]	May 31, 2010 UAB [Member]	Jun. 30, 2000 Emory University [Member]
Collaborative and Other Research and Development Contracts (Textual) [Abstract]
Collaborative agreement period of agreement			4 years
Collaborative agreement contract value			$ 102,661
Collaborative agreement adjusted contract value				234,852
Collaborative agreement additional contract value	55,000	77,191
Collaborative agreement additional contract period		12 months
Contract term	24 months
Up-front payment receivable amount						10,000
Deferred revenue up-front payment receivable						10,000
License fee received					250
Deferred revenue initiation of clinic trail payment received						5,000
Purchase of drug substance for forodesine						901
Potential milestone payments receivable						15,000
Unamortized deferred revenue, related to Amended and Restated Agreement							7,766
Deferred amounts equal reduction to valuation						2,337
Unamortized deferred expenses, related to Amended and Restated Agreement							1,864
Advance notice period for termination of agreement									60 days		90 days
Milestone payment minimum									1,400
Milestone payment maximum									4,000
Annual license fees minimum									150
Annual license fees maximum									500
Stock issued during period value for modification of license agreement								5,911
Payments for modification of license agreement								$ 90
Period of agreement										25 years
Renewable period of agreement										5 years