Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Stock-based compensation costs
Stock based compensation costs	$ 13,788	$ 12,582	$ 40,042	$ 36,893
Income tax benefit	817	619	1,951	7,515
Share based compensation costs after tax	12,971	11,963	38,091	29,378
Total unrecognized compensation costs related to awards	69,100		$ 69,100
Weighted-average period of recognition of unrecognized compensation costs			2 years 2 months 12 days
Cost of revenues
Stock-based compensation costs
Stock based compensation costs	344	324	$ 989	914
Research and development
Stock-based compensation costs
Stock based compensation costs	6,474	6,016	19,030	17,454
Selling, general and administrative
Stock-based compensation costs
Stock based compensation costs	$ 6,970	$ 6,242	$ 20,023	$ 18,525

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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