Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 38,130	$ 42,533
Unrealized Holdings Gains	6	1
Unrealized Holdings Losses	57	46
Fair Value	38,079	42,488
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,731	19,941
Fair Value	13,731	19,941
Cash and Cash Equivalents \| Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,563	13,195
Fair Value	8,563	13,195
Cash and Cash Equivalents \| Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,168	6,746
Fair Value	5,168	6,746
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,110	15,710
Unrealized Holdings Gains	2	1
Unrealized Holdings Losses	43	13
Fair Value	20,069	15,698
Short-term Investments \| Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	500	500
Unrealized Holdings Losses	1	3
Fair Value	499	497
Short-term Investments \| U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,912	4,917
Unrealized Holdings Losses	15	4
Fair Value	5,897	4,913
Short-term Investments \| Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,060	4,502
Unrealized Holdings Losses	25	5
Fair Value	6,035	4,497
Short-term Investments \| Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,145	2,500
Unrealized Holdings Gains	2	1
Unrealized Holdings Losses	2	1
Fair Value	7,145	2,500
Short-term Investments \| Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	493	3,291
Fair Value	493	3,291
Other Long-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,289	6,882
Unrealized Holdings Gains	4
Unrealized Holdings Losses	14	33
Fair Value	4,279	6,849
Other Long-term Investments \| Asset backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		500
Fair Value		500
Other Long-term Investments \| Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	499
Unrealized Holdings Losses	2
Fair Value	497
Other Long-term Investments \| U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	998	1,998
Unrealized Holdings Losses	7	12
Fair Value	991	1,986
Other Long-term Investments \| Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,792	4,384
Unrealized Holdings Gains	4
Unrealized Holdings Losses	5	21
Fair Value	$ 2,791	$ 4,363

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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