Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Jan. 03, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jan. 03, 2015	Dec. 28, 2013	Dec. 29, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 83,600us-gaap_SalesRevenueNet	$ 86,570us-gaap_SalesRevenueNet	$ 99,320us-gaap_SalesRevenueNet	$ 96,637us-gaap_SalesRevenueNet	$ 89,519us-gaap_SalesRevenueNet	$ 87,154us-gaap_SalesRevenueNet	$ 84,694us-gaap_SalesRevenueNet	$ 71,158us-gaap_SalesRevenueNet	$ 366,127us-gaap_SalesRevenueNet	$ 332,525us-gaap_SalesRevenueNet	$ 279,256us-gaap_SalesRevenueNet
Gross margin	46,263us-gaap_GrossProfit	50,811us-gaap_GrossProfit	54,975us-gaap_GrossProfit	54,138us-gaap_GrossProfit	48,603us-gaap_GrossProfit	46,376us-gaap_GrossProfit	45,110us-gaap_GrossProfit	38,155us-gaap_GrossProfit
Restructuring charges	1	2	3	11	131	85	19	153	17	388	6,018
Net income (loss)	$ 15,419us-gaap_NetIncomeLoss	$ 9,406us-gaap_NetIncomeLoss	$ 11,771us-gaap_NetIncomeLoss	$ 11,984us-gaap_NetIncomeLoss	$ 6,547us-gaap_NetIncomeLoss	$ 8,844us-gaap_NetIncomeLoss	$ 5,040us-gaap_NetIncomeLoss	$ 1,890us-gaap_NetIncomeLoss	$ 48,580us-gaap_NetIncomeLoss	$ 22,321us-gaap_NetIncomeLoss	$ (29,606)us-gaap_NetIncomeLoss
Basic net (loss) income per share (in dollars per share)	$ 0.13us-gaap_EarningsPerShareBasic	$ 0.08us-gaap_EarningsPerShareBasic	$ 0.10us-gaap_EarningsPerShareBasic	$ 0.10us-gaap_EarningsPerShareBasic	$ 0.06us-gaap_EarningsPerShareBasic	$ 0.08us-gaap_EarningsPerShareBasic	$ 0.04us-gaap_EarningsPerShareBasic	$ 0.02us-gaap_EarningsPerShareBasic	$ 0.41us-gaap_EarningsPerShareBasic	$ 0.19us-gaap_EarningsPerShareBasic	$ (0.25)us-gaap_EarningsPerShareBasic
Diluted net (loss) income per share (in dollars per share)	$ 0.13us-gaap_EarningsPerShareDiluted	$ 0.08us-gaap_EarningsPerShareDiluted	$ 0.10us-gaap_EarningsPerShareDiluted	$ 0.10us-gaap_EarningsPerShareDiluted	$ 0.06us-gaap_EarningsPerShareDiluted	$ 0.08us-gaap_EarningsPerShareDiluted	$ 0.04us-gaap_EarningsPerShareDiluted	$ 0.02us-gaap_EarningsPerShareDiluted	$ 0.40us-gaap_EarningsPerShareDiluted	$ 0.19us-gaap_EarningsPerShareDiluted	$ (0.25)us-gaap_EarningsPerShareDiluted

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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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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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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Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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