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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 |  |

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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 + Details
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