Nature of Business and Summary of Significant Accounting Policies - Number of Shares Outstanding for Calculation of Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ 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
Earnings Per Share [Abstract]
Basic net income and earnings per share, Numerator (Income)	$ (3,211)	$ (4,825)	$ 2,104	$ 198	$ 1,860	$ 3,703	$ 4,493	$ 3,021	$ (5,602)	$ 13,077	$ 6,557
Diluted net income and earnings per share, Numerator (Income)									$ (5,602)	$ 13,077	$ 6,557
Basic net income and earnings per share, Denominator (Shares)									28,791,662	25,750,972	20,116,991
Common stock equivalents arising from stock options and employee stock purchase plan, Denominator (Shares)										446,000	603,000
Diluted net income and earnings per share Denominator (Shares)									28,791,662	26,196,901	20,719,951
Basic net income and earnings per share, Per Share Amount	$ (0.09)	$ (0.17)	$ 0.08	$ 0.01	$ 0.07	$ 0.14	$ 0.18	$ 0.12	$ (0.19)	$ 0.51	$ 0.33
Common stock equivalents arising from stock options and employee stock purchase plan, Per share amount										(0.01)	(0.01)
Diluted net income and earnings per share	$ (0.09)	$ (0.17)	$ 0.08	$ 0.01	$ 0.07	$ 0.14	$ 0.17	$ 0.12	$ (0.19)	$ 0.50	$ 0.32