Net Income Per Share - Reconciliation used in Computing Basic and Diluted Net Income (Loss) per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 1,138	$ 184	$ 1,595	$ (59)	$ 1,017	$ 1,073	$ 169	$ 1,864	$ 2,858	$ 4,123	$ 40,155
Denominator:
Shares used in computation of basic net income per share (weighted average common shares outstanding)	28,305	28,190	28,070	27,818	27,733	28,505	28,383	28,370	28,097	28,246	28,190
Dilutive potential common shares:
Stock options, ESPP, Restricted Stock and RSUs (in shares)									918	898	1,148
Shares used in computation of diluted net income per share (in shares)	29,322	29,134	28,906	27,818	28,430	29,351	29,210	29,382	29,015	29,144	29,338
Basic net income per share:
Basic net income per share (in dollars per share)	$ 0.04	$ 0.01	$ 0.06	$ 0.00	$ 0.04	$ 0.04	$ 0.01	$ 0.07	$ 0.10	$ 0.15	$ 1.42
Diluted net income per share:
Diluted net income per share (in dollars per shares)	$ 0.04	$ 0.01	$ 0.06	$ 0.00	$ 0.04	$ 0.04	$ 0.01	$ 0.06	$ 0.10	$ 0.14	$ 1.37