Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	12 Months Ended							12 Months Ended					1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Sep. 30, 2012	Nov. 30, 2010	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	May 01, 2012	Jul. 30, 2009	Jun. 30, 2009	Mar. 20, 2009	Sep. 30, 2011 Sale Agreement Two [Member]	Sep. 30, 2013 Warrant One [Member]	Sep. 30, 2012 Warrant One [Member]	Sep. 30, 2013 Warrant Two [Member]	Sep. 30, 2012 Cantor [Member]	Aug. 31, 2012 August 2012 [Member]	Sep. 30, 2013 August 2012 [Member]	Jul. 31, 2013 July 2013 [Member]	Sep. 30, 2013 July 2013 [Member]	Sep. 30, 2013 Restricted stock units [Member]	Sep. 30, 2012 Restricted stock units [Member]	Sep. 30, 2011 Restricted stock units [Member]	Nov. 30, 2010 Common Stock [Member]	Sep. 30, 2013 Common Stock [Member]	Sep. 30, 2012 Common Stock [Member]	Sep. 30, 2011 Common Stock [Member]
Stockholders Equity [Line Items]
Percentage of share holding interest for exercise of right										20.00%
Preferred stock, Right redeemed										$ 0.0001
Redemption of right minimum acquisition percentage of outstanding common stock										20.00%
Preferred stock Right expiration Date				Mar. 20, 2019
Aggregate of common stock preferred stock debt securities and warrants limit under shelf registration																$ 100,000,000		$ 150,000,000
Maximum proceeds from the sale of common stock though an at-the-market facility																25,000,000		25,000,000
Common stock issued			12,355,166		3,668,656												7,935,395		5,030,070				20,000,000	12,965,465	3,668,656	22,327,000
Common stock issued average price per share	$ 2.81		$ 2.81		$ 2.81				$ 2.83		$ 3.78						$ 3.15		$ 4.97			$ 3.92
Proceeds from issuances of common stock																	25,000,000		25,000,000
Net of offering costs	33,800,000	83,000,000			10,100,000						7,900,000						24,400,000		24,400,000
Restricted stock units released, previously vested				510,188
Common stock issued in connection with vesting of restricted stock units				336,349	204,176
Stock issued during period, stock options exercised				1,033,833	1,673,811																			1,033,833	1,673,811	814,454
Proceeds form stock options exercised				1,500,000	1,300,000	638,000
Restricted stock units awards																				176,839	187,083	255,343
Maximum shares of common stock to be sold through an at-the-market facility								12,500,000
Proceed from issuance of common stock			35,000,000	48,752,806	10,062,996	90,851,876					8,100,000				10,300,000								88,000,000
Proceeds from warrant exercises				$ 1,000,000	$ 7,800,000
Common stock issued upon cashless exercise of warrants												710,109	5,445,061	72,185
Average exercise price of warrants outstanding	$ 1.43		$ 1.43	$ 1.43	$ 1.43
Common stock offering price per share		$ 4.40
Issued shares of common stock											2,147,000
Restricted stock units, Shares																								846,537	204,176	252,941
Common stock surrendered																										1,446
Warrants, Expiration Date				May 2022
Warrants to purchase shares							491,007
Warrant exercise price				2.78
Warrants exercised														437,050
Warrants outstanding to purchase shares	1,201,116		1,201,116	53,957	1,201,116	6,155,170								53,957