Income Per Common Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Options outstanding for the purchase of common stock	66,330	60,838	66,330	60,838
Shares included in computation of earnings per share	7,085	10,152	9,427	11,074
Preferred stock convertible into common stock at rate of shares of common stock	64,000	64,000	64,000	64,000
Shares attributable to conversion of preferred stock included in computation of earnings per share	64,000	64,000	64,000	64,000