Warrants - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010 Person
Class of Warrant or Right [Line Items]
Exercise price of common stock warrants to purchase	1.79	0.33
Number of executive officers who helds warrants			2
Common shares issued on exercise of warrants	105,000	1,526,182
Scenario 1
Class of Warrant or Right [Line Items]
Numbers of common stock warrants to purchase			1,526,182
Exercise price of common stock warrants to purchase			0.33
Scenario 2
Class of Warrant or Right [Line Items]
Numbers of common stock warrants to purchase			105,000
Exercise price of common stock warrants to purchase			1.79