Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) - USD ($) $ in Thousands	Sep. 29, 2018	Dec. 30, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 44,130	$ 42,533
Unrealized Holdings Gains	3	1
Unrealized Holdings Losses	41	46
Fair Value	44,092	42,488
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21,753	19,941
Fair Value	21,753	19,941
Cash and Cash Equivalents \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	809
Fair Value	809
Cash and Cash Equivalents \| Cash
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,408	13,195
Fair Value	15,408	13,195
Cash and Cash Equivalents \| Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,536	6,746
Fair Value	5,536	6,746
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,199	15,710
Unrealized Holdings Gains	2	1
Unrealized Holdings Losses	26	13
Fair Value	17,175	15,698
Short-term Investments \| Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	499	500
Unrealized Holdings Losses	2	3
Fair Value	497	497
Short-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,123	4,917
Unrealized Holdings Losses	12	4
Fair Value	5,111	4,913
Short-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,054	4,502
Unrealized Holdings Losses	12	5
Fair Value	3,042	4,497
Short-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,797	2,500
Unrealized Holdings Gains	2	1
Unrealized Holdings Losses		1
Fair Value	5,799	2,500
Short-term Investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,726	3,291
Fair Value	2,726	3,291
Other Long-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,178	6,882
Unrealized Holdings Gains	1
Unrealized Holdings Losses	15	33
Fair Value	5,164	6,849
Other Long-term Investments \| Asset backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		500
Fair Value		500
Other Long-term Investments \| U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	999	1,998
Unrealized Holdings Losses	9	12
Fair Value	990	1,986
Other Long-term Investments \| Corporate bonds and medium-term notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,679	4,384
Unrealized Holdings Gains	1
Unrealized Holdings Losses	6	21
Fair Value	3,674	$ 4,363
Other Long-term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	500
Fair Value	$ 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)
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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

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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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