Subsequent Events - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		0 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Oct. 09, 2013 Subsequent Event [Member] Stock Issued in Underwritten Public Offering [Member]	Sep. 30, 2013 Subsequent Event [Member] Stock Issued in Underwritten Public Offering [Member]
Subsequent Event [Line Items]
Number of common shares issued	27,520,527	26,229,909		11,000,000
Common stock, public offering price per share			$ 4.10	$ 4.10
Net proceeds from issuance of common stock	$ 2,004		$ 47,400	$ 42,400
Number of additional common shares issued to underwriters through over-allotment option			1,311,698