Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended			112 Months Ended	12 Months Ended			1 Months Ended		12 Months Ended					12 Months Ended		1 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended					24 Months Ended		1 Months Ended	12 Months Ended			12 Months Ended							12 Months Ended	1 Months Ended	12 Months Ended					12 Months Ended					12 Months Ended		1 Months Ended	12 Months Ended			12 Months Ended							12 Months Ended
	Jan. 06, 2011	May 27, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2012 Harmon Hill LLC Collaboration Agreement	Dec. 31, 2011 Harmon Hill LLC Collaboration Agreement	Dec. 31, 2010 Harmon Hill LLC Collaboration Agreement	Apr. 08, 2008 Harmon Hill LLC Collaboration Agreement Upon the dosing of the first patient	Apr. 08, 2008 Harmon Hill LLC Monthly Payment Collaboration Agreement	Dec. 31, 2012 Solasia	Dec. 31, 2012 Solasia Development-based milestones	Dec. 31, 2012 Solasia Sales-based milestones	Dec. 31, 2004 DEKK Tec Inc	Oct. 15, 2004 DEKK Tec Inc	Dec. 31, 2006 DEKK Tec Inc Upon the dosing of the first patient	Dec. 31, 2010 DEKK Tec Inc Phase 3	Mar. 16, 2010 DEKK Tec Inc Upon receiving a United States Patent for palifosfamide	Oct. 15, 2004 DEKK Tec Inc Up Front Payment	Dec. 31, 2012 Intrexon Corporation	Jan. 06, 2011 Intrexon Corporation Quarterly Payment	Dec. 31, 2012 Southern Research Institute	Dec. 31, 2011 Southern Research Institute	Dec. 31, 2010 Southern Research Institute	Dec. 31, 2009 Southern Research Institute	Dec. 31, 2008 Southern Research Institute	Dec. 21, 2006 Southern Research Institute Execution Agreement	Dec. 21, 2006 Southern Research Institute Maximum	Aug. 24, 2004 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Patent	Dec. 31, 2007 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System	Dec. 31, 2004 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System	Dec. 31, 2012 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System	Dec. 31, 2005 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Upon the commencement of Phase 1 clinical trial	Dec. 31, 2006 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Upon the dosing of the first patient	Dec. 31, 2007 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Intellectual Property Rights	Dec. 31, 2006 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Intellectual Property Rights	Dec. 31, 2005 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Upon the filing of an Investigation New Drug application (IND) for darinaparsin	Dec. 31, 2007 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Upon the completion of dosing of the last patient for both Phase 1 clinical trials	Dec. 31, 2012 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Upon enrollment of the first patient in a multi-center pivotal clinical trial	Dec. 31, 2004 The University Of Texas M.D. Anderson Cancer Center And The Texas A& M University System Up Front Payment	Nov. 03, 2006 Baxter Healthcare Corporation	Dec. 31, 2007 Baxter Healthcare Corporation Upon the successful U.S. IND application for indibulin	Nov. 03, 2006 Baxter Healthcare Corporation Assets	Nov. 03, 2006 Baxter Healthcare Corporation Inventories	Nov. 03, 2006 Baxter Healthcare Corporation Royalty Payments	Jun. 29, 2010 PPD Development L. P.	Dec. 31, 2010 PPD Development L. P. Upon a clinical study commencement of enrollment in North America	Dec. 31, 2010 PPD Development L. P. Upon contract execution	Dec. 31, 2012 PPD Development L. P. Upon initial clinical study enrollment	Dec. 31, 2011 PPD Development L. P. Upon initial clinical study enrollment	Dec. 13, 2011 Pharmaceutical Research Associates Inc	Dec. 31, 2012 Pharmaceutical Research Associates Inc Upon the achievement of various milestones	Nov. 02, 2012 Novella Clinical, Inc.	Nov. 02, 2012 Novella Clinical, Inc. Upon the achievement of various milestones	Dec. 31, 2012 New York, NY sqft	Jan. 31, 2012 New York, NY sqft	Dec. 31, 2011 New York, NY sqft	Dec. 31, 2012 Boston, MA sqft	Dec. 31, 2011 Boston, MA	Dec. 31, 2011 Boston, MA The first floor sqft	Jun. 30, 2012 Boston, MA The second floor sqft	Dec. 31, 2011 Boston, MA The second floor sqft	Dec. 31, 2011 Boston, MA The third floor sqft	Jun. 30, 2012 Boston, MA The four floor sqft	Dec. 31, 2012 Germantown, MD	Dec. 31, 2011 Germantown, MD	Apr. 30, 2011 Germantown, MD sqft
Commitments and Contingencies Disclosure [Line Items]
Office space under operating lease																																																								7,259		6,251				4,113			9,800			2,227
Letter of credit																																																										$ 388,000
Additional office space under operating lease																																																									1,008
Letter of credit collateral																																																								388,000
Operating lease expiration month and year																																																								2018-10			2016-08								2014-03
Operating lease space																																																											26,433		5,249		8,538	6,959
Security deposits																																																											127,000	86,000					41,000		4,000
Office closing date																																																																		Jul. 16, 2012
Total rent Expense			1,100,000	647,000	398,000	4,200,000
Deferred rent liability - current			39,000	15,000		39,000
Deferred rent liability - long term			400,000	180,000		400,000
Deferred rent liability net			439,000	195,000		439,000
Number of products																														2
Licensing fee																				50,000																					125,000
Shares of common stock granted			2,309,650	1,894,300	1,293,000																											250,487
Option to purchase common stock		1,050,000													27,616																	50,222
Sale of stock ,price per share															$ 0.02																	$ 0.002
Shares vested															6,904			6,904																				12,555	25,111
Stock based compensation expenses			4,880,000	2,759,000	3,637,000	20,181,000																									120,000
Shares expected to vest																																								12,556
Milestone payment																	100,000	300,000	100,000															100,000	250,000	100,000	100,000						625,000					1,100,000	1,800,000	3,800,000	4,000,000		7,300,000		256,000
Milestone maximum payment																4,000,000							775,000										4,500,000													8,000,000	23,000,000					19,700,000		789,000
Research expenses	17,500,000		83,446,000	57,083,000	12,910,000	212,345,000																						25,000	200,000
Royalty payment																							25,000	25,000	25,000	25,000	25,000
Asset Purchase Agreement, additional cash payment for inventory																																												1,100,000	100,000
Annual patent and license prosecution/maintenance fee																																										15,000
Milestones under the license agreement expense			250,000	0	0
Percent of company net profit							1.00%															50.00%
Percentage of revenue agreed to pay which is obtained from sublicensor																						50.00%
Contract termination description																					Our obligation to pay 50% of net profits or revenue described above with respect to these "retained" products will survive termination of the Channel Agreement.
Other expense							200,000	240,000	240,000
Payment for consulting services fee										500,000	20,000
Upfront payment received												5,000,000
Expected Additional milestone payments to be received													$ 32,500,000	$ 53,500,000