Warrants - Summary of Warrants to Purchase Common Stock Issued and Outstanding (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Oct. 31, 2012
Class of Warrant or Right [Line Items]
Investor warrants outstanding	3,674,444
Warrant exercise price		1.66
Warrants Weighted average exercise price	$ 1.38
Warrants Weighted average life in years	4 years 1 month 24 days
Equity Securities [Member] | Derivative with Exercise Price One [Member]
Class of Warrant or Right [Line Items]
Warrants Issued Year	2010
Investor warrants outstanding	1,637,449
Warrant exercise price	1.40
Equity Securities [Member] | Derivative with Exercise Price Two [Member]
Class of Warrant or Right [Line Items]
Warrants Issued Year	2010
Investor warrants outstanding	1,641,642
Warrant exercise price	1.00
Equity Securities [Member] | Derivative with Exercise Price Three [Member]
Class of Warrant or Right [Line Items]
Warrants Issued Year	2011
Investor warrants outstanding	16,071
Warrant exercise price	1.40
Investment Warrants Expiration Date	Jun. 17, 2018
Equity Securities [Member] | Derivative with Exercise Price Four [Member]
Class of Warrant or Right [Line Items]
Warrants Issued Year	2011
Investor warrants outstanding	343,137
Warrant exercise price	3.06
Investment Warrants Expiration Date	Dec. 21, 2016
Equity Securities [Member] | Derivative with Exercise Price Five [Member]
Class of Warrant or Right [Line Items]
Warrants Issued Year	2012
Investor warrants outstanding	36,145
Warrant exercise price	1.66
Investment Warrants Expiration Date	Oct. 05, 2019
Minimum [Member] | Equity Securities [Member] | Derivative with Exercise Price One [Member]
Class of Warrant or Right [Line Items]
Investment Warrants Expiration Date	Oct. 26, 2017
Minimum [Member] | Equity Securities [Member] | Derivative with Exercise Price Two [Member]
Class of Warrant or Right [Line Items]
Investment Warrants Expiration Date	Oct. 26, 2017
Maximum [Member] | Equity Securities [Member] | Derivative with Exercise Price One [Member]
Class of Warrant or Right [Line Items]
Investment Warrants Expiration Date	Dec. 03, 2017
Maximum [Member] | Equity Securities [Member] | Derivative with Exercise Price Two [Member]
Class of Warrant or Right [Line Items]
Investment Warrants Expiration Date	Dec. 03, 2017