Long-Term Debt (Details) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2021 USD ($) $ / shares	Jul. 04, 2020 USD ($)	Jul. 03, 2021 USD ($) $ / shares	Jul. 04, 2020 USD ($)	Dec. 31, 2020 USD ($)
Debt Instruments [Abstract]
Credit facility	$ 0		$ 0		$ 0
Deferred financing costs	(11,313)		(11,313)		(11,512)
Long-term debt	454,031		454,031		394,886
Less current portion	0		0		0
Long-term debt, less current portion	454,031		454,031		394,886
Interest expense [Abstract]
Contractual coupon interest		$ 3,282		$ 6,701
Non-cash amortization of debt discount		3,488	0	7,125
Other non-cash interest expense (income)		435		889
Total interest expense related to the debentures		7,205		14,715
Purchase price of extinguished debt			300	90,525
Loss on extinguishment of debt, including the write-off of portion of unamortized debt issuance costs	0	(1,146)	0	(4,066)
Convertible Senior Notes, Due 2025 [Member]
Debt Instruments [Abstract]
Convertible debt	$ 465,344		$ 465,344		406,268
Issuance date			Jun. 12, 2018
Debt maturity date			Jun. 15, 2025
Cash coupon rate	2.25%		2.25%
Nonconvertible debt borrowing rate at issuance	5.50%		5.50%
Effective conversion rate			31.9104
Effective conversion price (in dollars per share) | $ / shares	$ 31.34		$ 31.34
130% of the conversion price (in dollars per share) | $ / shares			$ 40.74
Debt instrument percentage of conversion price			130.00%
Debt instrument percentage of sales price of common stock	98.00%		98.00%
Maximum threshold of quarterly cash dividends per share of common stock for not adjusting conversion rate of convertible notes | $ / shares			$ 0.085
Liability and equity components of convertible debentures [Abstract]
Principal amount of debt	$ 465,344		$ 465,344
Interest expense [Abstract]
Contractual coupon interest	2,618	3,266	5,236	6,641
Non-cash amortization of debt discount	0	3,479	0	7,096
Other non-cash interest expense (income)	433	435	866	889
Total interest expense related to the debentures	3,051	7,180	6,102	14,626
Convertible Senior Debentures, Due 2040 [Member]
Debt Instruments [Abstract]
Convertible debt	$ 0		$ 0		130
Convertible Senior Debentures [Member]
Interest expense [Abstract]
Contractual coupon interest		16		60
Non-cash amortization of debt discount		9		29
Other non-cash interest expense (income)		0		0
Total interest expense related to the debentures		$ 25		$ 89
Convertible Debt [Member]
Liability and equity components of convertible debentures [Abstract]
Principal amount of debt					465,644
Unamortized discount					(59,246)
Carrying value of liability component					406,398
Equity component - net carrying value					66,248
Convertible Debt [Member] | Convertible Senior Notes, Due 2025 [Member]
Liability and equity components of convertible debentures [Abstract]
Principal amount of debt					465,344
Unamortized discount					(59,076)
Carrying value of liability component					406,268
Equity component - net carrying value					66,127
Convertible Debt [Member] | Convertible Senior Debentures, Due 2040 [Member]
Liability and equity components of convertible debentures [Abstract]
Principal amount of debt					300
Unamortized discount					(170)
Carrying value of liability component					130
Equity component - net carrying value					$ 121