Public Offering of Common Stock - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Apr. 30, 2014	Dec. 31, 2014	Apr. 14, 2014
Equity [Abstract]
Common stock to be sold, shares			12,500,000
Public offering price	$ 4.00		$ 4.00
Expected aggregate gross proceeds			$ 50,000,000
Value of stock to be purchased by existing stockholders			10,000,000
Over-allotment option, shares to be issued to underwriters			1,875,000
Shares issued from option exercise by underwriters	1,610,000
Additional proceeds from exercise of option by underwriters	6,400,000
Proceeds from the issuance of common shares	52,400,000	52,433,000
Issuance costs of Issuance of common shares	4,000,000
Aggregate maximum value of designated securities to be sold	$ 100,000,000