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Marketable Securities - Available-for-sale Securities by Major Security Type (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Marketable Securities [Line Items] |  |
Amortized cost | $ 3,933 | $ 4,521
Gross unrealized holding gains | 46 | 26
Gross unrealized holding losses | (8) | (4)
Estimated fair value | 3,971 | 4,543
Corporate bonds and notes [Member] |  |
Marketable Securities [Line Items] |  |
Amortized cost | 1,916 | 1,814
Gross unrealized holding gains | 37 | 21
Gross unrealized holding losses | (8) | (3)
Estimated fair value | 1,945 | 1,832
Municipal bonds [Member] |  |
Marketable Securities [Line Items] |  |
Amortized cost | 2,017 | 2,707
Gross unrealized holding gains | 9 | 5
Gross unrealized holding losses |  | (1)
Estimated fair value | $ 2,026 | $ 2,711

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + 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=118939692&loc=d3e27161-111563 + Details
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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References No definition available. + Details
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- Definition This item represents the cost of debt and equity 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. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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