Note 1 - General and Basis of Presentation - Customers as a Percentage of Total Revenues (Details) - Revenue Benchmark [Member] - Customer Concentration Risk [Member]	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Southern California Public Power Authority [Member]
Percent of revenues	26.70%	21.90%
Sierra Pacific Power Company And Nevada Power Company [Member]
Percent of revenues	18.90%	19.50%
Kenya Power and Lighting Co LTD [Member]
Percent of revenues	14.50%	14.10%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 275
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-Section 50
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482861/275-10-50-20

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