Organization and Basis of Presentation - Additional Information (Detail) (USD $)	1 Months Ended
	Jul. 27, 2012	Jul. 31, 2012
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Net proceeds from a public offering (Offering) of common stock and warrants	$ 65,363,000
Underwriting discounts and commissions paid	4,205,000
Estimated offering expenses	$ 549,000
Sale of shares of common stock	32,500,000
Sale of warrants to purchase common stock	14,625,000
Purchase price of common stock per share	$ 1.99
Purchase price of common stock per share underlying each warrant	$ 0.01
Number of days underwriters granted to cover over-allotments	30 days
Purchase additional common stock	4,875,000
Option to purchase additional warrants	2,193,750
Common stock underwriters exercised shares common stock	2,558,300
Warrants underwriters exercised shares common stock	1,151,235
Warrants exercise price per share	$ 2.50	$ 2.50
Warrants exercisable date	Jul. 27, 2013	Jul. 27, 2013
Warrants expiry date	July 27, 2017	July 27, 2017
Warrant expiration period from the date of issuance (in years)	5 years