Common Stock Offering - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012
Subsidiary, Sale of Stock [Line Items]
Net proceeds from common stock	$ 8,695,566
Expenses for issuance of stock	$ 654,434
Private Placement
Subsidiary, Sale of Stock [Line Items]
Common stock sold	2,200,000
Common stock at purchase price	$ 4.25