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Fair Value of Financial Instruments - Available-for-sale investments (Details) - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2018 | Dec. 30, 2017
Cost |  |
Due in one year or less, Cost | $ 313,832 |
Due after one year through ten years, Cost | 131,655 |
Due after ten years, Cost | 24,042 |
Total Cost | 469,529 |
Fair Value |  |
Due in one year or less, Fair Value | 313,333 |
Due after one year through ten years, Fair Value | 130,420 |
Due after ten years, Fair Value | 23,681 |
Total Fair Value | 467,434 |
Continuous unrealized loss position, Fair Value |  |
Fair value of available-for-sale securities, continuous loss position for less than twelve months | 280,445 | $ 396,029
Fair value of available-for-sale securities, continuous loss position for twelve months or greater | 20,063 | 20,286
Total fair value of available-for-sale securities, continuous loss position | 300,508 | 416,315
Continuous unrealized loss position, Gross Unrealized Losses |  |
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses | (1,683) | (1,378)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses | (434) | (407)
Available-for-sale securities, total gross unrealized losses | (2,117) | (1,785)
Other than temporary impairment losses |  |
Other-than-temporary impairment losses | 0 |
Government debt securities |  |
Continuous unrealized loss position, Fair Value |  |
Fair value of available-for-sale securities, continuous loss position for less than twelve months | 153,566 | 244,880
Fair value of available-for-sale securities, continuous loss position for twelve months or greater | 3,269 | 3,027
Total fair value of available-for-sale securities, continuous loss position | 156,835 | 247,907
Continuous unrealized loss position, Gross Unrealized Losses |  |
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses | (893) | (931)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses | (6) | (15)
Available-for-sale securities, total gross unrealized losses | (899) | (946)
Corporate debt securities |  |
Continuous unrealized loss position, Fair Value |  |
Fair value of available-for-sale securities, continuous loss position for less than twelve months | 126,879 | 151,149
Fair value of available-for-sale securities, continuous loss position for twelve months or greater | 11,152 | 11,578
Total fair value of available-for-sale securities, continuous loss position | 138,031 | 162,727
Continuous unrealized loss position, Gross Unrealized Losses |  |
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses | (790) | (447)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses | (70) | (73)
Available-for-sale securities, total gross unrealized losses | (860) | (520)
Auction rate securities |  |
Continuous unrealized loss position, Fair Value |  |
Fair value of available-for-sale securities, continuous loss position for twelve months or greater | 5,642 | 5,681
Total fair value of available-for-sale securities, continuous loss position | 5,642 | 5,681
Continuous unrealized loss position, Gross Unrealized Losses |  |
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses | (358) | (319)
Available-for-sale securities, total gross unrealized losses | $ (358) | $ (319)

X
- Definition This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after one year and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor as trading securities. + References No definition available. + Details
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- Definition This item represents the fair value of debt securities, which are expected to mature after one year and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor as trading securities. + References No definition available. + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer. + References No definition available. + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References No definition available. + Details
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- Definition Amount after adjustments of available-for-sale debt securities at cost, maturing after the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27198-111563 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 + Details
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