Convertible Preferred Stock And Stockholders' Equity (Summary Of Option And Stock Appreciation Rights Activity) (Details) - Stock Options And Stock Appreciation Rights [Member] - $ / shares	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options/SARs, Outstanding, December 31, 2017	413,301
Number of Options/SARs, Granted	858,500
Number of Options/SARs, Exercised
Number of Options/SARs, Forfeited	(35,356)
Number of Options/SARs, Outstanding, March 31, 2018	1,236,445	413,301
Weighted Average Exercise Price per Share, Outstanding, December 31, 2017	$ 9.04
Weighted Average Exercise Price per Share, Granted	0.74
Weighted Average Exercise Price per Share, Exercised
Weighted Average Exercise Price per Share, Forfeited	9.14
Weighted Average Exercise Price per Share, Outstanding, March 31, 2018	3.27	$ 9.04
$0.62 - $54.90 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit		0.62
Range of Exercise Price, Upper Limit		$ 54.90
$0.74 - $0.83 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit	0.74
Range of Exercise Price, Upper Limit	0.83
$2.15 - $32.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit	2.15
Range of Exercise Price, Upper Limit	35.20
$0.62 - $54.90 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit	0.62
Range of Exercise Price, Upper Limit	$ 54.90

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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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.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Number of share options (or share units) exercised during the current period.

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