Note 12 - Related-party Transactions (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Due from Related Parties, Current, Total	$ 369	$ 507
Ergon [Member]
Revenue from Related Parties	49,600	44,400
Due from Related Parties, Current, Total	400	500
Deferred Revenue, Total	9,300	8,800
Ergon [Member] \| Cimarron Express [Member]
Due to Related Parties, Contingent Liability			$ 12,200
Ergon [Member] \| Crude Oil Purchase Agreement [Member]
Related Party Transaction, Purchases from Related Party	9,500	92,100
Ergon [Member] \| Ergon 2020 Master Storage, Throughput and Handling Agreement [Member]
Operating Lease, Lease Income, Total	39,500	16,800
Ergon [Member] \| Ergon Operating and Maintenance Agreement [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$ 18,600	7,700
Ergon [Member] \| Ergon Lessee Operated Facility Lease Agreement [Member]
Operating Lease, Lease Income, Total		4,400
Ergon [Member] \| Ergon 2016 Storage and Handling Agreement [Member]
Revenue from Related Parties		12,000
Ergon [Member] \| Ergon Fontana and Las Vegas Storage Throughput and Handling Agreement [Member]
Revenue from Related Parties		$ 3,500

Represents contingent liability due to related parties.

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Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable.

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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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Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

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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.

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