Common Stock - Additional Information (Detail) (J. P. Morgan Securities LLC, USD $)	1 Months Ended
	Jan. 25, 2012	Jan. 31, 2012	Jan. 20, 2012
Class of Stock [Line Items]
Issuance & sale of common stock in Public offering			9,650,000
Issuance & sale of common stock in Public offering price per share			$ 5.20
sale of stock Price per share			$ 4.888
Option exercise period			30 days
Option to purchase common stock			1,447,500
Stock issued during period	9,650,000	464,401
Proceeds from issuance of common stock		$ 49,200,000
Total
Class of Stock [Line Items]
Stock issued during period		10,114,401