Balance Sheet Components (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 03, 2021	Sep. 27, 2020	Oct. 03, 2021	Sep. 27, 2020
Balance Sheet Related Disclosures [Abstract]
Provisions for excess and obsolete inventory	$ 700	$ 1,800	$ 3,045	$ 6,353
Amortization expense	200	$ 1,500	1,900	$ 4,700
Equity securities without readily determinable fair value, cumulative downward adjustments for price change and impairment loss	8,400		8,400
Cumulative upward adjustments for price changes	$ 200		$ 200

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.

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Amount of cumulative impairment loss on investment in equity security without readily determinable fair value.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
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Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

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Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

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