Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Total assets measured at fair value	$ 52,038	$ 59,183
Cash and cash equivalents [Member] \| Money market funds [Member]
ASSETS
Total cash and cash equivalents	7,773	50,703
Investments [Member] \| U.S. Treasury Securities [Member]
ASSETS
Total investments	44,265	8,480
Level 1 [Member]
ASSETS
Total assets measured at fair value	7,773	50,703
Level 1 [Member] \| Cash and cash equivalents [Member] \| Money market funds [Member]
ASSETS
Total cash and cash equivalents	7,773	50,703
Level 2 [Member]
ASSETS
Total assets measured at fair value	44,265	8,480
Level 2 [Member] \| Investments [Member] \| U.S. Treasury Securities [Member]
ASSETS
Total investments	$ 44,265	$ 8,480

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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