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Note 6 - Share-based Compensation (Details Textual) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($) shares	Dec. 31, 2021	Dec. 31, 2020
Number Of Active Stock Incentive Plans	1
Performance Shares [Member]
Performance Share Award Target Level, Percentage	100.00%
Performance Awards Issued Multiplier		93.00%	141.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number At Target Level Of Performance (in shares) | shares	69,000
Performance Shares [Member] | Minimum [Member]
Performance Awards Issued Multiplier	0.00%
Performance Shares [Member] | Maximum [Member]
Performance Awards Issued Multiplier	200.00%
Restricted Stock Units and Performance Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | $	$ 2
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	1 year 6 months

X

- Definition

The number of active stock incentive plans.

+ References

No definition available.

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X

- Definition

The percentage of the performance awards issued multiplier.

+ References

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+ Details

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X

- Definition

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+ References

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+ Details

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X

- Definition

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

+ References

No definition available.

+ Details

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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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