Organization and Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding and Income Per Share (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Numerator for basic and diluted earnings per share:
Net income	$ 4,457,534	$ 3,442,247	$ 7,755,355	$ 7,246,065
Denominator:
Weighted average shares outstanding - basic	51,109,060	54,520,889	51,923,097	58,849,010
Dilutive effect of stock-based awards	1,744,106	645,755	1,775,690	633,664
Diluted weighted average shares outstanding	52,853,166	55,166,644	53,698,787	59,482,674
Anti-dilutive stock-based awards excluded	1,235,117	5,346,367	1,234,221	6,534,472
Basic	$ 0.09	$ 0.06	$ 0.15	$ 0.12
Diluted	$ 0.08	$ 0.06	$ 0.14	$ 0.12