Cash, Cash Equivalents and Investments - Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) - USD ($) $ in Thousands	Mar. 28, 2020	Dec. 28, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 42,395	$ 41,981
Unrealized Holding Gains	77	43
Unrealized Holding Losses	32	0
Fair Value	42,440	42,024
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21,450	19,767
Fair Value	21,450	19,767
Cash and Cash Equivalents \| Cash
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,782	16,512
Fair Value	17,782	16,512
Cash and Cash Equivalents \| Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,168	3,255
Fair Value	3,168	3,255
Cash and Cash Equivalents \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	500
Fair Value	500
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,436	16,691
Unrealized Holding Gains	23	29
Unrealized Holding Losses	18	0
Fair Value	16,441	16,720
Short-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,309	6,383
Unrealized Holding Gains	5	25
Unrealized Holding Losses	8	0
Fair Value	7,306	6,408
Short-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,433	5,417
Unrealized Holding Gains	12	1
Fair Value	3,445	5,418
Short-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,800	3,000
Unrealized Holding Gains	5	1
Unrealized Holding Losses	9	0
Fair Value	3,796	3,001
Short-term Investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,894	1,891
Unrealized Holding Gains	1	2
Unrealized Holding Losses	1	0
Fair Value	1,894	1,893
Long-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,509	5,523
Unrealized Holding Gains	54	14
Unrealized Holding Losses	14	0
Fair Value	4,549	5,537
Long-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,015	2,530
Unrealized Holding Gains	3	12
Unrealized Holding Losses		0
Fair Value	1,018	2,542
Long-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,495	2,494
Unrealized Holding Gains	49	1
Unrealized Holding Losses	0	0
Fair Value	2,544	2,495
Long-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	999	499
Unrealized Holding Gains	2	1
Unrealized Holding Losses	14
Fair Value	$ 987	$ 500

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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