Note 3 - Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue	$ 69,125	$ 74,863	$ 171,948	$ 233,280
Revenue	16,632	16,871	46,290	46,183
Total revenue	85,757	91,734	218,238	279,463
Operating Segments [Member]
Total revenue	87,191	93,376	222,602	284,434
Asphalt Terminalling Services [Member]
Total revenue	28,995	28,126	80,436	79,324
Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	12,363	11,255	34,146	33,141
Revenue	16,632	16,871	46,290	46,183
Total revenue	28,995	28,126	80,436	79,324
Crude Oil Terminalling Services [Member]
Total revenue	4,190	4,503	12,613	12,668
Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue	4,190	4,225	12,613	11,815
Revenue
Total revenue	4,190	4,225	12,613	11,815
Crude Oil Pipeline Services [Member]
Total revenue	51,802	56,561	120,355	179,787
Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue	51,802	56,561	120,355	179,787
Revenue
Total revenue	51,802	56,561	120,355	179,787
Crude Oil Trucking Services [Member]
Total revenue	2,204	4,186	9,198	12,655
Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue	770	2,822	4,834	8,537
Revenue
Total revenue	770	2,822	4,834	8,537
Third Party [Member]
Revenue	9,142	11,444	27,051	31,004
Third Party [Member] \| Asphalt Terminalling Services [Member]
Revenue	9,142	11,444	27,050	31,004
Related Party [Member]
Revenue	7,490	5,427	19,239	15,179
Related Party [Member] \| Asphalt Terminalling Services [Member]
Revenue	7,490	5,427	19,240	15,179
Fixed Storageand Throughput Revenue [Member] \| Third Party [Member]
Revenue	8,424	8,272	25,176	24,232
Fixed Storageand Throughput Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	5,097	5,008	15,318	14,852
Fixed Storageand Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue	3,327	3,264	9,858	9,380
Fixed Storageand Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Fixed Storageand Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Fixed Storageand Throughput Revenue [Member] \| Related Party [Member]
Revenue	4,079	2,813	9,861	8,525
Fixed Storageand Throughput Revenue [Member] \| Related Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	4,079	2,750	9,861	8,296
Fixed Storageand Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Fixed Storageand Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue		63		229
Fixed Storageand Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Variable Throughput Revenue [Member] \| Third Party [Member]
Revenue	1,615	1,609	3,884	3,312
Revenue	713	1,451	746	1,451
Variable Throughput Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	752	648	1,129	877
Revenue	713	1,451	746	1,451
Variable Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue	863	961	2,755	2,435
Revenue
Variable Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Throughput Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Throughput Revenue [Member] \| Related Party [Member]
Revenue	267	21	647	136
Revenue	784	615	784	615
Variable Throughput Revenue [Member] \| Related Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	267	21	647	136
Revenue	784	615	784	615
Variable Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Throughput Revenue [Member] \| Related Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Reimbursement Revenue [Member] \| Third Party [Member]
Revenue	1,665	1,729	4,754	5,489
Revenue	499	578	1,576	1,685
Variable Reimbursement Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	1,665	1,729	4,754	5,489
Revenue	499	578	1,576	1,685
Variable Reimbursement Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Reimbursement Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Reimbursement Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Reimbursement Revenue [Member] \| Related Party [Member]
Revenue	503	1,100	2,437	3,528
Revenue	154	79	541	316
Variable Reimbursement Revenue [Member] \| Related Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	503	1,099	2,437	3,491
Revenue	154	79	541	316
Variable Reimbursement Revenue [Member] \| Related Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Variable Reimbursement Revenue [Member] \| Related Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue		1		37
Revenue
Variable Reimbursement Revenue [Member] \| Related Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Revenue
Crude Oil Transportation Revenue [Member] \| Third Party [Member]
Revenue	1,182	4,106	6,121	14,285
Crude Oil Transportation Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Crude Oil Transportation Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Crude Oil Transportation Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue	412	1,284	1,287	5,748
Crude Oil Transportation Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue	770	2,822	4,834	8,537
Crude Oil Product Sales Revenue [Member] \| Third Party [Member]
Revenue	51,390	55,213	119,068	173,773
Crude Oil Product Sales Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Crude Oil Product Sales Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Crude Oil Product Sales Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue	51,390	55,213	119,068	173,773
Crude Oil Product Sales Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Third Party [Member]
Revenue	7,930	9,415	24,729	27,867
Fixed Lease Revenue [Member] \| Third Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	7,930	9,415	24,729	27,867
Fixed Lease Revenue [Member] \| Third Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Third Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Third Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Related Party [Member]
Revenue	6,552	4,733	17,914	14,249
Fixed Lease Revenue [Member] \| Related Party [Member] \| Asphalt Terminalling Services [Member] \| Operating Segments [Member]
Revenue	6,552	4,733	17,914	14,249
Fixed Lease Revenue [Member] \| Related Party [Member] \| Crude Oil Terminalling Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Related Party [Member] \| Crude Oil Pipeline Services [Member] \| Operating Segments [Member]
Revenue
Fixed Lease Revenue [Member] \| Related Party [Member] \| Crude Oil Trucking Services [Member] \| Operating Segments [Member]
Revenue