Organization and Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding and Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator for basic and diluted earnings per share:
Net income	$ 2,083	$ 5,711	$ 8,485	$ 12,926	$ (2,071)	$ 422	$ 2,276	$ 4,580	$ 29,205	$ 5,207	$ 17,297
Denominator:
Weighted average shares outstanding—basic (in shares)									56,392	52,726	52,667
Dilutive effect of stock-based awards (in shares)									1,530	1,172	869
Diluted weighted average shares outstanding (in shares)									57,922	53,898	53,536
Anti-dilutive stock-based awards excluded (in shares)									6,757	386	443
Net income per common share:
Basic (in dollars per share)	$ 0.04	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.52	$ 0.10	$ 0.33
Diluted (in dollars per share)	$ 0.03	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.50	$ 0.10	$ 0.32