Common Stock Warrant Liability - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Jul. 31, 2011	Jun. 11, 2010	Dec. 31, 2012	Dec. 31, 2011	Apr. 30, 2011
Common Stock Warrant [Line Items]
Warrant issued to purchase common stock		15	15
Aggregate purchase price of common stock warrant		$ 300,000	$ 300,000
Common stock warrants expiration date		2020-06
Common stock warrants exercise price	0.664	1.03	1.03		0.690
Warrant vested upon issuance		20.00%
Common stock warrants annual vesting percentage on each anniversary date		20.00%
Common stock warrants percentage vested			60.00%
Proceeds from issuance of warrants		$ 200,000	$ 60,000	$ 60,000
Common stock issued as purchase consideration	3.0
Price per share of common stock issued	$ 0.664
Percentage of common stock warrants waiving protection provisions	79.30%