Common Stock - Additional Information (Detail) (J. P. Morgan Securities LLC [Member], USD $)	1 Months Ended
	Jan. 20, 2012	Jan. 25, 2012	Jan. 31, 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, Shares, New Issues		9,650,000	464,401
Proceeds from issuance of common stock			$ 49,200,000
Total [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues			10,114,401