Stock Options And Employee Stock Purchase Plan (Narrative) (Details) - USD ($)	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Number of options outstanding	747,996		375,675
Cash received upon the issuance of common stock	$ 64,000	$ 67,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Estimated Forfeiture Rate	10.74%	15.31%
Restricted (Performance) Stock [Member]
Shares, Granted	400,000	0
Restricted Stock [Member]
Shares, Granted	612,547
Number of stocks outstanding	1,190,581		605,566
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	5 years 8 months 27 days
Employee Stock Option [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 7,700,000		$ 200,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	7 years 6 months 26 days
Restricted Stock Units (RSUs) [Member]
Shares, Granted	12,614
Number of stocks outstanding	47,994		38,400
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 5 months 23 days
2001 Employee Stock Purchase Plan [Member] \| Common Stock [Member]
Market value of common stock on the date of grant for incentive stock options	95.00%
Maximum earnings withheld by the employees	15.00%
Number of shares purchased under the plan	851	837
Cash received upon the issuance of common stock	$ 65,000	$ 67,000
Number of shares available for issuance	1,622,392
2007 Stock Plan [Member]
Number of options outstanding	285,996
Number of stocks outstanding	8,840
Maximum issuance of common stock	4,500,000
2015 Stock Option Plan [Member]
Number of options outstanding	462,000
Number of stocks outstanding	39,154
Maximum issuance of common stock	4,200,000
Minimum [Member]
Market value of common stock on the date of grant for incentive stock options	85.00%

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Estimated Forfeiture Rate

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The cash inflow associated with the amount received from the stock plan during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
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Discount rate from fair value on offering date that participants pay for shares.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (a)(3)
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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

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

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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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