Note 9 - Leases - Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Operating leases	$ 2,074	$ 2,142	$ 6,337	$ 6,381
Variable lease expense	523	570	1,602	1,765
Short-term operating leases	15	80	53	224
Amortization of leased assets	17	20	65	82
Interest on lease liabilities	0	29	57	117
Sublease income	(31)	(31)	(94)	(101)
Net lease cost	$ 2,598	$ 2,810	$ 8,020	$ 8,468

Amount of interest expense on finance lease liability.

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Amount of amortization expense attributable to right-of-use asset from finance lease.

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Amount of lease cost recognized by lessee for lease contract.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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Amount of sublease income excluding finance and operating lease expense.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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