Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 40,677	$ 39,190
Unrealized Holdings Gains	27	5
Unrealized Holdings Losses	9	32
Fair Value	40,695	39,163
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,536	18,715
Unrealized Holdings Gains	1
Fair Value	23,537	18,715
Cash and Cash Equivalents \| Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	500
Fair Value	500
Cash and Cash Equivalents \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,804	2,046
Unrealized Holdings Gains	1
Fair Value	1,805	2,046
Cash and Cash Equivalents \| Cash
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14,671	13,334
Fair Value	14,671	13,334
Cash and Cash Equivalents \| Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,064	3,335
Fair Value	5,064	3,335
Cash and Cash Equivalents \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,497
Fair Value	1,497
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	11,766	16,097
Unrealized Holdings Gains	6	1
Unrealized Holdings Losses	8	22
Fair Value	11,764	16,076
Short-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,807	4,759
Unrealized Holdings Gains	2
Unrealized Holdings Losses	3	13
Fair Value	2,806	4,746
Short-term Investments \| Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	500	500
Unrealized Holdings Losses		2
Fair Value	500	498
Short-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,560	3,297
Unrealized Holdings Losses	5	5
Fair Value	3,555	3,292
Short-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,000	5,299
Unrealized Holdings Gains	4	1
Unrealized Holdings Losses		1
Fair Value	3,004	5,299
Short-term Investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,899	2,242
Unrealized Holdings Losses		1
Fair Value	1,899	2,241
Other Long-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,375	4,378
Unrealized Holdings Gains	20	4
Unrealized Holdings Losses	1	10
Fair Value	5,394	4,372
Other Long-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,875	2,879
Unrealized Holdings Gains	20	4
Unrealized Holdings Losses	1	4
Fair Value	4,894	2,879
Other Long-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		999
Unrealized Holdings Losses		6
Fair Value		993
Other Long-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	500	500
Fair Value	$ 500	$ 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=82897076&loc=d3e27161-111563

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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