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Note 4 - Fair Value Measurements (Details Textual) - Lucid [Member] - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Cost Method Investments	$ 0	$ 0
Cost Method Investment, Cumulative Impairment Losses	$ 2,000,000

X

- Definition

The accumulated decrease in the carrying value of cost method investments.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: