Note 5 - Sale of Equity Interests in Rio Bravo Pipeline Company, LLC (Details Textual) - Rio Bravo [Member] - USD ($) $ in Millions	Mar. 02, 2020	Feb. 13, 2020	Dec. 31, 2020
Equity Method Investment, Ownership Percentage		100.00%
Disposal Group, Including Discontinued Operation, Consideration	$ 19.4
Proceeds from Divestiture of Businesses	$ 15.0
Equity Method Investments, Rights to The Natural Gas Firm Transportation Capacity Term (Year)		20 years
Sale of Business, Failure to Issue Notice, Maximum Right Price to Sell Back Equity Interests			$ 23.0

Represents percentage of business ownership sold.

No definition available.

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- Definition

Represents term of rights to the natural gas firm transportation capacity.

+ References

No definition available.

+ Details

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- Definition

The maximum right price to sell back equity interests after the failure to issue a notice in the sale of a business.

+ References

No definition available.

+ Details

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- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

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