Marketable Securities (Schedule Of Cost And Fair Value Of Marketable Securities) (Details) - USD ($) |
Mar. 31, 2018 |
Dec. 31, 2017 |
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| Schedule of Available-for-sale Securities [Line Items] | ||
| Cost Basis | $ 14,973,920 | $ 17,988,827 |
| Gross Unrealized Losses | (89,376) | (56,886) |
| Fair value | 14,884,544 | 17,931,941 |
| Commercial Paper [Member] | ||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Cost Basis | 1,247,021 | 3,241,005 |
| Gross Unrealized Losses | (1,758) | (2,505) |
| Fair value | 1,245,263 | 3,238,500 |
| Corporate Bonds [Member] | ||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Cost Basis | 13,726,899 | 14,747,822 |
| Gross Unrealized Losses | (87,618) | (54,381) |
| Fair value | $ 13,639,281 | $ 14,693,441 |
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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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