Note 19 - Operating Segments - Financial Data for Each Segment (Details) - USD ($) $ in Thousands		3 Months Ended												12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018		Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2019	Dec. 31, 2018
Revenue from contract with customer														$ 308,915	$ 316,807
Revenues		$ 91,506	$ 91,756	$ 94,076	$ 93,732	$ 123,524	[1]	$ 133,158		$ 83,493		$ 44,660		371,070	384,835	[1]
Operating margin, excluding depreciation and amortization														75,833	71,059
Total assets (end of period)		301,940				323,304								301,940	323,304
Depreciation and amortization														(25,533)	(29,359)
General and administrative expenses														(14,095)	(15,995)
Asset impairment expense						(52,400)								(2,476)	(53,068)
Gain on sale of assets														453	149
Other income														268
Gain on sale of unconsolidated affiliate															2,225
Interest expense														(15,975)	(16,860)
Income (loss) before income taxes														18,475	(41,849)
Intersegment Eliminations [Member]
Revenues														(6,486)	(5,284)
Operating Segments [Member]
Revenues														377,556	390,119
Operating margin, excluding depreciation and amortization	[2]													75,833	71,059
Third Party [Member]
Lease revenue														41,712	42,067
Cost of product sales														83,319	126,776
Related Party [Member]
Lease revenue														20,443	25,961
Cost of product sales														134,162	102,469
Asphalt Terminalling Services [Member]
Revenue from contract with customer														44,476	48,276
Revenues														106,631	115,556
Operating expense, excluding depreciation and amortization														46,271	49,229
Operating margin, excluding depreciation and amortization														60,360	66,327
Additions to long-lived assets														7,841	30,068
Total assets (end of period)		140,299				138,245								140,299	138,245
Asphalt Terminalling Services [Member] | Third Party [Member]
Lease revenue														41,712	41,319
Asphalt Terminalling Services [Member] | Related Party [Member]
Lease revenue														20,443	25,961
Crude Oil Trucking Services [Member]
Revenue from contract with customer														11,066	14,334
Revenues														16,621	19,133
Operating expense, excluding depreciation and amortization														16,211	19,575
Operating margin, excluding depreciation and amortization														410	(442)
Additions to long-lived assets														2,168	3,243
Total assets (end of period)		5,590				4,150								5,590	4,150
Crude Oil Trucking Services [Member] | Third Party [Member]
Lease revenue															219
Crude Oil Terminalling Services [Member]
Revenue from contract with customer														15,365	11,928
Revenues														16,296	12,677
Operating expense, excluding depreciation and amortization														4,531	3,899
Operating margin, excluding depreciation and amortization														11,765	8,778
Additions to long-lived assets														883	3,394
Total assets (end of period)		65,112				68,480								65,112	68,480
Crude Oil Terminalling Services [Member] | Third Party [Member]
Lease revenue															45
Crude Oil Pipeline Services [Member]
Revenue from contract with customer														238,008	242,269
Revenues														238,008	242,753
Operating expense, excluding depreciation and amortization														10,743	11,828
Operating margin, excluding depreciation and amortization														3,298	(3,604)
Additions to long-lived assets														1,854	19,654
Total assets (end of period)		$ 90,939				$ 112,429								90,939	112,429
Crude Oil Pipeline Services [Member] | Intersegment Eliminations [Member]
Intersegment operating expense														6,486	5,284
Crude Oil Pipeline Services [Member] | Third Party [Member]
Lease revenue															484
Cost of product sales														83,319	126,776
Crude Oil Pipeline Services [Member] | Related Party [Member]
Cost of product sales														134,162	102,469
Service [Member] | Third Party [Member]
Revenue from contract with customer														61,811	58,756
Service [Member] | Related Party [Member]
Revenue from contract with customer														16,053	22,131
Service [Member] | Asphalt Terminalling Services [Member] | Third Party [Member]
Revenue from contract with customer														28,689	26,108
Service [Member] | Asphalt Terminalling Services [Member] | Related Party [Member]
Revenue from contract with customer														15,787	21,686
Service [Member] | Crude Oil Trucking Services [Member] | Intersegment Eliminations [Member]
Revenue from contract with customer														5,555	4,580
Service [Member] | Crude Oil Trucking Services [Member] | Third Party [Member]
Revenue from contract with customer														11,066	14,324
Service [Member] | Crude Oil Terminalling Services [Member] | Intersegment Eliminations [Member]
Revenue from contract with customer														931	704
Service [Member] | Crude Oil Terminalling Services [Member] | Third Party [Member]
Revenue from contract with customer														15,365	11,928
Service [Member] | Crude Oil Pipeline Services [Member] | Third Party [Member]
Revenue from contract with customer														6,691	6,396
Service [Member] | Crude Oil Pipeline Services [Member] | Related Party [Member]
Revenue from contract with customer														266	445
Product [Member] | Third Party [Member]
Revenue from contract with customer														231,051	235,438
Product [Member] | Related Party [Member]
Revenue from contract with customer															482
Product [Member] | Asphalt Terminalling Services [Member] | Related Party [Member]
Revenue from contract with customer															482
Product [Member] | Crude Oil Trucking Services [Member] | Third Party [Member]
Revenue from contract with customer															10
Product [Member] | Crude Oil Pipeline Services [Member] | Third Party [Member]
Revenue from contract with customer														$ 231,051	$ 235,428

[1] The increase in revenue during 2018 is due to an increase in volume in the Partnership's crude oil marketing business.

[2] The following table reconciles segment operating margin (excluding depreciation and amortization) to income before income taxes (in thousands):