Note 8 - Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 29, 2020	Sep. 28, 2019	Sep. 29, 2020	Sep. 28, 2019
Amortization of intangible assets	$ 620	$ 3,403	$ 3,891	$ 10,209
Research and Development Expense [Member]
Amortization of intangible assets	17	14	45	41
Amortization of Acquired Intangible Assets [Member]
Amortization of intangible assets	$ 603	$ 3,389	$ 3,846	$ 10,168

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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