Warrants and Warrant Liabilities - Additional Information (Detail) (USD $)	0 Months Ended					1 Months Ended		3 Months Ended		6 Months Ended	12 Months Ended				162 Months Ended		0 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended					1 Months Ended	12 Months Ended				1 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	1 Months Ended
	Aug. 16, 2013	Mar. 28, 2012	Jul. 02, 2008	May 21, 2008	Feb. 04, 2008	Dec. 30, 2010	May 31, 2003	Jun. 30, 2013 Warrants	Jun. 30, 2008	Jun. 30, 2013 Warrants	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2002	Dec. 31, 2013	Aug. 31, 2001	May 06, 2013 Class B Warrants	May 06, 2013 Class A-2 Warrants	Jan. 31, 2013 Warrant	Jun. 30, 2013 Before Modification	Jun. 30, 2013 Before Modification	Jun. 30, 2013 After Modification	Jun. 30, 2013 After Modification	Dec. 31, 2013 Minimum	Jun. 30, 2013 Minimum Before Modification	Jun. 30, 2013 Minimum Before Modification	Jun. 30, 2013 Minimum After Modification	Jun. 30, 2013 Minimum After Modification	Dec. 31, 2013 Maximum	Jun. 30, 2013 Maximum Before Modification	Jun. 30, 2013 Maximum Before Modification	Jun. 30, 2013 Maximum After Modification	Jun. 30, 2013 Maximum After Modification	Dec. 31, 2008 Adoption of New Accounting Pronouncement Effect	Jan. 31, 2014 Subsequent Event Class A-2 Warrants	Apr. 30, 2009 Warrant 7	Dec. 31, 2012 Warrant 7	Dec. 31, 2011 Warrant 7	Dec. 31, 2010 Warrant 7	Dec. 31, 2010 Warrant 7 Vesting Scenario One	Dec. 31, 2010 Warrant 7 Vesting Scenario Two	May 31, 2009 Warrant 8	Dec. 31, 2013 Warrant 8	Dec. 31, 2010 Warrant 8	Dec. 31, 2013 Warrant Eleven	Dec. 31, 2012 Warrant Eleven	May 31, 2010 Warrant Eleven First Issuance	Dec. 31, 2010 Warrant Eleven First Issuance	May 31, 2010 Warrant Eleven Second Issuance	Dec. 31, 2011 Warrant Eleven Second Issuance	Dec. 31, 2010 Warrant Eleven Second Issuance	Dec. 31, 2013 Warrant Eleven Second Issuance	Dec. 31, 2011 Warrant Eleven Second Issuance Minimum	Dec. 31, 2010 Warrant Eleven Second Issuance Minimum	Dec. 31, 2011 Warrant Eleven Second Issuance Maximum	Dec. 31, 2010 Warrant Eleven Second Issuance Maximum	Jun. 30, 2010 Warrant Twelve	Dec. 31, 2011 Warrant Twelve	Dec. 31, 2010 Warrant Twelve	Dec. 31, 2013 Warrant Twelve	Dec. 31, 2010 Warrant Thirteen First Issuance	Dec. 31, 2010 Warrant Thirteen First Issuance	Dec. 31, 2010 Warrant Thirteen Second Issuance	May 31, 2008 Investor Relations Group
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Issued											6,035,229				6,035,229		4,000,000																		500,000								6,250		14,584							7,500								100,000
Value of warrants																																			$ 1,500,000	$ 32,000		$ 104,000		$ 16,000	$ 124,000	$ 232,000					$ 134,000		$ 40,000												$ 112,000		$ 2,000	$ 3,000
Warrants issued in period	0	46,378	50,000		1,400	500	18,269							18,334																																																		6,500
Exercise price of warrant			6.00		9.00	7.20	32.40							21.00		39.00			2.65																	3.00						3.00			13,750	6,667	4.50		15.00								4.26				3.90	3.90	7.20	3.00
Warrants exercise period																																																																3 years
Warrant, expiration year																																																																2011
Warrants to purchase shares of common stock																			5,000																	55,000						95,834					35,001		12,000								100,000				33,334	33,334	500
Vested warrant																																				13,334	33,333			8,334		74,000		74,000						7,500							25,000
Warrant that will vest upon the achievement of certain milestones																																				41,666					33,332																50,000
Expected life											5 years 3 months 15 days	5 years 9 months 22 days			5 years 2 months 9 days				3 years					5 years	9 months 7 days	9 months 7 days	5 years 9 months 11 days	5 years 9 months 11 days	10 years	2 years 4 days	2 years 4 days	7 years 7 days	7 years 7 days			4 years		1 year 3 months 15 days		3 years 22 days	2 years 3 months 15 days	5 years					4 years		4 years				2 years 11 months 27 days	3 years 4 months 24 days	3 years 3 months 26 days	3 years 11 months 27 days	4 years 3 months 11 days				5 years		5 years
Expected volatility of the underlying stock											115.00%	116.00%			119.00%				87.00%																	134.00%		70.00%		140.00%	141.00%	124.00%					143.00%		143.00%				128.00%	130.00%	130.00%	144.00%	135.00%				130.00%		130.00%
Risk free interest rate											1.17%	0.90%			1.68%				0.42%																	1.76%		0.12%		1.69%	0.61%	2.16%					1.61%		1.61%				0.79%	0.51%	1.29%	1.68%	1.705%				1.90%		2.06%
Expected dividend rate											0.00%	0.00%			0.00%				0.00%																	0.00%		0.00%		0.00%	0.00%	0.00%					0.00%		0.00%	0.00%	0.00%						0.00%				0.00%		0.00%
Stock-based compensation expense											3,789,000	2,792,000			16,163,000				7,000																				111,000					53,000				134,000		12,000	15,000							340,000	219,000			112,000
Reversal of stock-based compensation expense												100,000																										13,000
Forfeited warrant											1,344,012	616,726																														21,834		21,834						4,500
warrant exercised																																											67,750
Warrant vesting per month																																																	500
Warrant expected to vest in one year																																																									25,000
Warrants for purchase common stock shares																		1,000,000
Warrants exercisable life extended period																	5 years	5 years
Expense related to extension of warrants								8,763,000		8,763,000
Number of warrants required for extensions								5,000,000		5,000,000
Volatility rate,minimum																				77.00%	77.00%	113.00%	113.00%
Volatility rate,maximum																				96.00%	96.00%	122.00%	122.00%
Risk free interest,minimum																				0.11%	0.11%	0.74%	0.74%
Risk free interest,maximum																				0.22%	0.22%	1.19%	1.19%
Expected dividend payment																				0	0	0	0
Warrants issued																																		1,164,929
Decrease in additional paid-in-capital																																		458,000
Increase in warrant liabilities																																		204,000
Change in fair value of warrant liabilities				$ 100,000					$ 356,000				$ 524,000		$ (9,022,000)