Organization and Basis of Presentation - Narrative (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended
	Jul. 27, 2012	Jul. 18, 2011	Dec. 27, 2010 IPO [Member]	Nov. 29, 2010 IPO [Member]	Nov. 29, 2010 IPO [Member] Convertible Preferred Stock [Member]	Nov. 29, 2010 IPO [Member] Convertible Notes Payable [Member]
Disclosure Organization And Basis Of Presentation Additional Information [Abstract]
Net proceeds from a public offering (Offering) of common stock and warrants	$ 65,352
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 underlying each warrant (in usd per share)	$ 0.01
Number of days underwriters granted to cover over-allotments	30 days
Option to purchase additional warrants	2,193,750
Common stock underwriters exercised shares common stock	1,159,200
Warrants underwriters exercised shares common stock	2,558,300
Warrants exercisable date	Jul. 27, 2013
Warrants exercise price (in usd per share)	$ 2.50
Warrants expiry date	July 27, 2017
Period For Warrant Term	5 years	10 years
Shares of common stock exercisable through warrants	15,784,200
Class of Stock [Line Items]
Issuance of common stock from initial public offering, net of issuance costs of $6,013, shares				14,000,000
Purchase price of common stock (in usd per share)	$ 1.99			$ 4.00
Over-allotment options of additional shares	4,875,000			2,100,000
Shares sold from over-allotment option			436,493
Issuance of common stock from initial public offering				51,733
Underwriting discounts and commissions paid	4,205			2,743
Offering expenses	545			3,270
Conversion of convertible preferred stock to common stock at initial public offering, shares					14,239,797	3,873,756
Unsecured convertible notes				$ 15,495