Stockholders' Equity - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended				3 Months Ended		12 Months Ended		128 Months Ended		1 Months Ended		3 Months Ended	12 Months Ended					1 Months Ended			0 Months Ended	1 Months Ended			3 Months Ended
	Oct. 11, 2013	May 31, 2013	Jan. 31, 2013	Dec. 31, 2012	Aug. 10, 2012	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2013	Sep. 30, 2013	Nov. 17, 2011 Roche	May 31, 2013 Common Stock	Dec. 31, 2013 Common Stock	Sep. 30, 2013 Common Stock	Sep. 30, 2012 Common Stock	Sep. 30, 2011 Common Stock	Sep. 30, 2010 Common Stock	Sep. 30, 2005 Common Stock	Feb. 29, 2012 Series A Preferred Stock	Oct. 31, 2011 Series A Preferred Stock	Oct. 21, 2011 Series A Preferred Stock	Oct. 11, 2013 Series C Preferred Stock	May 31, 2013 Series B convertible preferred stock	Oct. 31, 2011 Subscription Agreement	Oct. 31, 2011 Subscription Agreement Series A Preferred Stock	Dec. 31, 2013 Limited liability company	Dec. 31, 2013 2004 Equity Incentive Plan, 2000 Stock Option Plan, and Inducement Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Capital stock authorized for issuance						150,000,000				150,000,000
Common stock, shares authorized						145,000,000				145,000,000	145,000,000
Common stock, par value						$ 0.001				$ 0.001	$ 0.001														$ 0.001
Preferred stock, shares authorized						5,000,000				5,000,000	5,000,000
Preferred stock, par value						$ 0.001				$ 0.001	$ 0.001									$ 0.001		$ 0.001
Common stock, shares outstanding						39,002,152				39,002,152	32,489,444
Preferred stock, shares outstanding						51,291				51,291	9,900
Share reserve for issuance																												3,451,210
Threshold percentage of common stock ownership upon preferred stock conversion						9.99%				9.99%
Maximum equity commitment amount under agreement																											$ 15,000,000
Equity commitment agreement period																											36 months
Cash drawn from facility																											1,000,000
Sale of stock, price per share	$ 5.86		$ 2.12	$ 2.26	$ 2.76		$ 2.26						$ 1.83									$ 1,000	$ 1,000	$ 1,000	$ 3.70
Aggregate purchase price of preferred shares								1,618,509	300,000												1,015,000
Issuance and sold of Common Stock	3,071,672		1,667,051	1,825,079	2,260,869								14,300,000	848,961	1,182,451	15,511	8,656	225,189	1,250				46,000	9,900	675,000	1,015
Number of shares converted in common stock																				1,015	1,015
Preferred stock converted to common stock, shares																				275,782
Aggregate purchase price on issuance of common stock to be received																									2,497,500
Proceeds from issuance of common stock, preferred stock and warrants, net	60,000,000		3,500,000	4,100,000	6,200,000	62,821,592	3,332,467			213,580,607
Unit sold, description			Each unit consisted of one share of common stock and a warrant to purchase	Each unit consisted of one share of common stock and a warrant to purchase	Each unit consisted of one share of common stock and a warrant to purchase
Warrant to purchase share of Common Stock			0.5	0.5	0.75		0.5
Common stock exercise price					$ 3.25
Exercise price of warrant											1.83
Conversion price	$ 5.86	$ 1.83
Cash from issuance of equity		36,000,000				60,000,000
Aggregate price on issuance or Sale of equity	$ 64,000,000
Reverse stock split ratio												0.1