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Note 6 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
	Mar. 07, 2018	Jan. 31, 2019	Apr. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Jul. 12, 2018
Property Subject to or Available for Operating Lease, Gross				$ 287,700
Property Subject to or Available for Operating Lease, Accumulated Depreciation				181,400
Depreciation, Total				22,500	$ 26,900
Proceeds from Sale of Property, Plant, and Equipment, Total				8,410	5,051
Gain (Loss) on Disposition of Property Plant Equipment, Total				453	149
Tangible Asset Impairment Charges, Total				274	42,860
Asphalt Terminalling Facility in Oklahoma [Member]
Business Combination, Consideration Transferred, Total	$ 22,000
Divestiture [Member] \| Disposal Group, Not Discontinued Operations [Member]
Disposal Group, Including Discontinued Operation, Consideration						$ 90,000
Producer Field Services Business [Member] \| Disposal Group, Not Discontinued Operations [Member]
Proceeds from Divestiture of Businesses			$ 3,000
Gain (Loss) on Disposition of Business			$ 400
Various Surplus Assets [Member]
Proceeds from Sale of Property, Plant, and Equipment, Total				5,700
Gain (Loss) on Disposition of Property Plant Equipment, Total				$ (500)
Pipeline Linefill [Member]
Proceeds from Sale of Property, Plant, and Equipment, Total		$ 2,600
Tangible Asset Impairment Charges, Total					1,700
Pipeline Systems [Member]
Tangible Asset Impairment Charges, Total					40,700
Truck Stations [Member]
Tangible Asset Impairment Charges, Total					$ 400