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Amortized Cost and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands | Dec. 29, 2018 | Dec. 30, 2017
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 113,359 | $ 111,142
Gross Unrealized Gains | 33 | 117
Gross Unrealized Losses | 1,217 | 340
Fair Value | 112,175 | 110,919
Money market investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 11,714 | 27,895
Fair Value | 11,714 | 27,895
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 624 | 2,805
Gross Unrealized Losses | 4 | 5
Fair Value | 620 | 2,800
Corporate bonds and direct obligations of government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 101,021 | 80,442
Gross Unrealized Gains | 33 | 117
Gross Unrealized Losses | 1,213 | 335
Fair Value | $ 99,841 | $ 80,224

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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References 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 + Details
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- Definition 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 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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