Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended						9 Months Ended		13 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Aug. 30, 2016
Equity [Abstract]
Common stock repurchase authorized										$ 5,000,000
Repurchase of common stock, shares	35,709			18,127			168,917	18,127	223,093
Repurchase of common stock, value	$ 641,000			$ 358,000			$ 3,177,865	$ 358,000	$ 4,322,000
Common stock repurchase, average price per share	$ 17.95						$ 18.81		$ 19.37
Dividends declared, per share	0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.51	$ 0.51
Dividends paid, per share	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.17
Dividend payments, amount	$ 1,974,000			$ 1,937,000			$ 5,911,617	$ 5,813,000