Computation of Basic and Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net income (loss)	$ 1,100	$ (3,490)	$ 2,929	$ (9,795)
Weighted-average shares - basic	21,495	20,691	21,356	20,621
Effect of dilutive potential common shares	1,714		1,643
Weighted-average shares - diluted	23,209	20,691	22,999	20,621
Net income (loss) per share - basic	$ 0.05	$ (0.17)	$ 0.14	$ (0.48)
Net income (loss) per share - diluted	$ 0.05	$ (0.17)	$ 0.13	$ (0.48)

Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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