Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	0 Months Ended	12 Months Ended			12 Months Ended							12 Months Ended				12 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended	0 Months Ended	9 Months Ended	12 Months Ended						24 Months Ended		9 Months Ended	0 Months Ended	12 Months Ended							0 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended		12 Months Ended			9 Months Ended	12 Months Ended	0 Months Ended		9 Months Ended		0 Months Ended	12 Months Ended					0 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	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	Jun. 30, 2014 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	Jun. 30, 2014 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	Dec. 31, 2005 DEKK Tec Inc	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	Dec. 31, 2011 DEKK Tec Inc Phase 3	Mar. 16, 2010 DEKK Tec Inc Upon receiving a United States Patent for palifosfamide	Dec. 31, 2009 DEKK Tec Inc Upon receiving a United States Patent for palifosfamide	Oct. 15, 2004 DEKK Tec Inc Up Front Payment	Sep. 30, 2014 Southern Research Institute	Dec. 31, 2013 Southern Research Institute	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	Sep. 30, 2014 Intrexon Corporation	Jan. 06, 2011 Intrexon Corporation Quarterly Payment	Dec. 31, 2013 PPD Development L. P.	Dec. 31, 2012 PPD Development L. P.	Dec. 31, 2011 PPD Development L. P.	Dec. 31, 2010 PPD Development L. P.	Dec. 31, 2013 Pharmaceutical Research Associates Inc Upon the achievement of various milestones	Dec. 31, 2012 Pharmaceutical Research Associates Inc Upon the achievement of various milestones	Nov. 02, 2012 Novella Clinical, Inc.	Aug. 18, 2014 Novella Clinical, Inc. After Amendment	Dec. 31, 2012 Novella Clinical, Inc. Upon the achievement of various milestones	Sep. 30, 2014 Novella Clinical, Inc. Upon two database related milestones	Dec. 31, 2013 Novella Clinical, Inc. Upon two database related milestones	Nov. 03, 2006 Baxter Healthcare Corporation	Dec. 31, 2013 Baxter Healthcare Corporation Upon the successful U.S. IND application for indibulin	Dec. 31, 2012 Baxter Healthcare Corporation Upon the successful U.S. IND application for indibulin	Dec. 31, 2007 Baxter Healthcare Corporation Upon the successful U.S. IND application for indibulin	Sep. 30, 2014 Harmon Hill LLC Collaboration Agreement	Dec. 31, 2013 Harmon Hill LLC Collaboration Agreement	Jun. 27, 2013 Harmon Hill LLC Collaboration Agreement Monthly Payment	Mar. 07, 2011 Solasia	Sep. 30, 2014 Solasia Development-based milestones	Sep. 30, 2014 Solasia Sales-based milestones	Oct. 17, 2013 New York, NY sqft	Dec. 31, 2013 New York, NY	Dec. 31, 2012 New York, NY sqft	Sep. 30, 2014 New York, NY	Jan. 31, 2012 New York, NY sqft	Dec. 31, 2011 New York, NY sqft	Aug. 30, 2013 Boston, MA sqft	Dec. 31, 2013 Boston, MA	Dec. 31, 2011 Boston, MA	Sep. 30, 2014 Boston, MA sqft	Dec. 31, 2012 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
Commitments and Contingencies Disclosure [Line Items]
Office space under operating lease																																																													7,259			6,251				21,184			4,113			9,800
Letter of credit																																																													$ 388,000	$ 388,000		$ 388,000
Additional office space under operating lease																																																															1,008
Operating lease expiration month and year																																																												2018-10	2018-10						2016-08
Area under sublease agreement																																																											7,259						5,249
Loss on sublease																																																												729,000						42,000
Remaining contractual obligation																																																												2,300,000						367,000
Sublease revenue from subtenant																																																												1,600,000						325,000
Loss on disposal of fixed assets				(194,000)																																																								(392,000)						(194,000)
Operating lease space																																																																						5,249		8,538	6,959
Security deposits																																																																				127,000	127,000					41,000
Security deposit from subtenant																																																																				20,000
Total rent Expense			445,000	889,000
Deferred rent - current portion	244,000		244,000		212,000
Deferred rent-non-current portion	665,000		665,000		851,000
Deferred rent liability net	909,000		909,000		1,100,000
Percent of company net profit																																					50.00%
Percentage of revenue agreed to pay which is obtained from sublicensor																																					50.00%
Contract termination description																																				The Company's obligation to pay 50% of net profits or revenue described above with respect to these "retained" products will survive termination of the Channel Agreement.
Licensing fee																	125,000									50,000
Milestone maximum payment									4,500,000											4,000,000							775,000																	790,000
Milestone payment										100,000	250,000	100,000	100,000								100,000	300,000		100,000	0													9,200,000	3,800,000	4,000,000	2,900,000	2,200,000	7,300,000			256,000	10,000	136,000		250,000	250,000	625,000
Option to purchase common stock								50,222											27,616
Sale of stock price per share								$ 0.002											$ 0.02
Shares vested														12,555	25,111				6,904			6,904
Shares exercised			585,638															6,904					6,904
Research expenses	9,733,000	6,247,000	24,621,000	40,133,000																														25,000	200,000
Royalty payment																											0	25,000	25,000	25,000	25,000	25,000	25,000
Number of products						2
Stock options, granted	10,000	125,000	114,300	1,551,400				250,487
Stock-based compensation	1,148,000	809,000	3,583,000	2,482,000			120,000
Shares expected to vest																12,556
Upfront payment received																																																								5,000,000
Expected Additional milestone payments to be received																																																									32,500,000	53,500,000
Deferred revenue - current portion	1,700,000		1,700,000		800,000
Research contract revenue	633,000	200,000	1,033,000	600,000
Estimated upfront payment for research and development funding earning period					75 months
Asset Purchase Agreement, upfront cash payment																																																	1,100,000
Asset Purchase Agreement, additional cash payment for existing inventory																																																	100,000
Payment for consulting services fee																																																					135,000	135,000	15,000
Total cost savings																																													$ 1,000,000