Convertible Debt - Interest (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jul. 02, 2021	Jun. 26, 2020	Jul. 02, 2021	Jun. 26, 2020
Convertible Note due 2022
Debt Instrument [Line Items]
Contractual interest expense	$ 412	$ 128	$ 824	$ 128
Amortization of debt discount	171	49	337	49
Amortization of debt issuance costs	53	15	105	15
Total interest expense recognized	636	192	1,266	192
Convertible Note due 2024
Debt Instrument [Line Items]
Contractual interest expense	578	578	1,156	1,156
Amortization of debt discount	1,166	1,077	2,312	2,134
Amortization of debt issuance costs	158	146	314	290
Total interest expense recognized	$ 1,902	$ 1,801	$ 3,782	$ 3,580

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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