Stock-Based Compensation - Stock-based compensation costs (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Stock-Based Compensation
Stock-based compensation cost	$ 50,077	$ 44,752	$ 39,628
Income tax benefit	8,890	11,073	8,496
Share based compensation costs after tax	41,187	33,679	31,132
Total unrecognized compensation costs related to awards	$ 65,400
Weighted-average period of recognition of unrecognized compensation costs	1 year 10 months 24 days
Reserved shares of common stock for future issuance	3,328
2009 Stock Incentive Plan
Stock-Based Compensation
Reserved shares of common stock for future issuance	2,343
2009 Employee Stock Purchase Plan
Stock-Based Compensation
Reserved shares of common stock for future issuance	985
Cost of revenues
Stock-Based Compensation
Stock-based compensation cost	$ 1,238	1,090	1,070
Research and development
Stock-Based Compensation
Stock-based compensation cost	23,867	21,771	19,573
Selling, general and administrative
Stock-Based Compensation
Stock-based compensation cost	$ 24,972	$ 21,891	$ 18,985

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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