Preferred Stock and Warrant - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2011	May. 13, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Limitations on payment of dividends on common stock	no more than 100% of the aggregate per share dividend
Dividend declared and paid, common stock		$ 0.15
Preferred stock, issued	17,123			17,123
Warrant Issued To Purchase Of Common Stock	54,705
Treasury Stock Redemption Amount			$ 302,410
Series CD Preferred Stock
Class of Stock [Line Items]
Preferred stock, annual dividend rate	2.00%
Capital purchase liquidation dividend term	8 years