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Note 5 - Acquisitions and Divestitures (Details Textual) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 04, 2019	Mar. 31, 2021	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Combination, Contingent Consideration, Liability, Total			$ 2,100		$ 1,800	$ 2,100
Proceeds from Divestiture of Businesses					$ 0	$ 0	$ 4,000
Waterstar [Member]
Proceeds from Divestiture of Businesses							4,000
Gain (Loss) on Disposition of Business							$ 1,000
Gaomei [Member]
Payments to Acquire Businesses, Gross			$ 11,300	$ 11,300
Business Combination, Contingent Consideration, Liability, Total	$ 4,700
Business Combination, Working Capital Adjustment	(200)
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 0
Gaomei [Member] | Minimum [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	10 years
Gaomei [Member] | Maximum [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	15 years
Gaomei [Member] | Forecast [Member]
Payment for Contingent Consideration Liability, Financing Activities		$ 1,800

X

- Definition

Estimated amount of working capital adjustment that is expected to impact the purchase price in a business combination

+ References

No definition available.

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

+ References

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

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Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

+ References

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Amount of cash outflow, not made soon after acquisition date of business combination, to settle contingent consideration liability up to amount recognized at acquisition date, including, but not limited to, measurement period adjustment and less amount paid soon after acquisition date.

+ References

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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