Marketable Securities (Schedule Of Cost And Fair Value Of Marketable Securities) (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	$ 11,905,421
Gross Unrealized Gains
Gross Unrealized Losses	(12,602)
Fair Value	11,892,819
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	5,902,433
Gross Unrealized Gains
Gross Unrealized Losses	(5,414)
Fair Value	5,897,019
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	6,002,988	$ 5,999,356
Gross Unrealized Gains
Gross Unrealized Losses	(7,188)	(17,836)
Fair Value	$ 5,995,800	$ 5,981,520

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

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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

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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.

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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.

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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.

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