Balance Sheet Components (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 27, 2021	Jun. 28, 2020	Jun. 27, 2021	Jun. 28, 2020
Balance Sheet Related Disclosures [Abstract]
Provisions for excess and obsolete inventory	$ 1,100	$ 2,200	$ 2,255	$ 4,579
Amortization expense	200	$ 1,600	1,700	$ 3,200
Equity securities without readily determinable fair value, cumulative downward adjustments for price change and impairment loss	7,900		7,900
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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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
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Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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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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-Publisher FASB
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