Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Net income (loss)	$ (16,029)	$ 14,280	$ (10,631)	$ 40,685
Shares used in computing basic earnings (loss) per share	43,386	43,312	43,287	43,138
Effect of dilutive securities:
Stock-based awards and convertible debt		982		968
Shares used in computing diluted earnings (loss) per share	43,386	44,294	43,287	44,106
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.37)	$ 0.33	$ (0.25)	$ 0.94
Diluted (in dollars per share)	$ (0.37)	$ 0.32	$ (0.25)	$ 0.92
Shares excluded from computation of diluted earning per share	600		600
Shares attributable to dilutive effect of conversion of debt securities	200	300	100	200