Organization and Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding and Income Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator for basic and diluted earnings per share:
Net income	$ 5,113,592	$ 3,676,872	$ 12,868,947	$ 10,922,936
Denominator:
Weighted average shares outstanding-basic	51,341,785	52,509,068	51,727,197	57,997,341
Dilutive effect of stock-based awards	1,979,133	597,257	1,916,606	485,492
Diluted weighted average shares outstanding	53,320,918	53,106,325	53,643,803	58,482,833
Anti-dilutive stock-based awards excluded	565,099	4,732,366	898,230	5,261,887
Net income per common share:
Basic	$ 0.10	$ 0.07	$ 0.25	$ 0.19
Diluted	$ 0.10	$ 0.07	$ 0.24	$ 0.19