Note 9 - Related-party Transactions (Details Textual) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Due from Related Parties, Current, Total	$ 615		$ 369
Ergon [Member]
Revenue from Related Parties	12,400	$ 11,900
Due from Related Parties, Current, Total	600		400
Deferred Revenue, Total	6,000		$ 9,300
Ergon [Member] \| Ergon Operating and Maintenance Agreement [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$ 4,800	$ 4,600

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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+ Details

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

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+ Details