Stockholders' Equity - Additional Information (Detail) - USD ($)				12 Months Ended
	Nov. 02, 2015	Oct. 27, 2014	Oct. 28, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders Equity Note [Line Items]
Special cash dividend declared, date	Nov. 02, 2015	Oct. 27, 2014	Oct. 28, 2013
Special cash dividend record, date	Nov. 13, 2015	Nov. 07, 2014	Nov. 08, 2013
Special cash dividend declared per share	$ 0.55	$ 0.50	$ 0.35
Special cash dividend paid	$ 36,455,955	$ 32,977,016	$ 22,982,447	$ 36,455,955	$ 32,977,016	$ 22,982,447
Special cash dividend paid, date	Jan. 04, 2016	Nov. 20, 2014	Jan. 02, 2014
Common stock, shares outstanding	65,618,141	65,298,472	64,987,854	65,636,707	65,303,205
Dividend equivalent paid per share on unvested shares of restricted stock outstanding on the dividend record date granted under the Company's 2006 Stock Option and Incentive Plan	$ 0.55	$ 0.50	$ 0.35
Unvested shares of restricted stock on the dividend record date	665,414	655,499	676,281