Convertible Notes, Other Debts And Capital Leases - Interest (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Debt Disclosure [Abstract]
Contractual interest expense	$ 1,283	$ 1,283	$ 3,848	$ 3,848
Amortization of debt discount	1,364	1,235	4,001	3,623
Amortization of debt issuance costs	164	149	481	437
Total interest expense recognized	$ 2,811	$ 2,667	$ 8,330	$ 7,908

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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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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