Note 4 - Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Total revenue	$ 115,417	$ 110,245
Fixed Storageand Throughput Revenue [Member]
Total revenue	39,198	34,834
Fixed Lease Revenue [Member]
Total revenue	58,405	56,754
Variable Cost Recovery Revenue [Member]
Total revenue	12,066	12,664
Variable Throughput Revenue [Member]
Total revenue	5,748	5,993
Third Party [Member]
Revenue	30,715	29,171
Operating Lease, Lease Income, Total	35,065	36,630
Third Party [Member] | Fixed Storageand Throughput Revenue [Member]
Revenue	20,315	20,303
Operating Lease, Lease Income, Total	0	0
Third Party [Member] | Fixed Lease Revenue [Member]
Revenue	0	0
Operating Lease, Lease Income, Total	31,263	32,207
Third Party [Member] | Variable Cost Recovery Revenue [Member]
Revenue	8,616	6,620
Operating Lease, Lease Income, Total	1,816	2,205
Third Party [Member] | Variable Throughput Revenue [Member]
Revenue	1,784	2,248
Operating Lease, Lease Income, Total	1,986	2,218
Related Party [Member]
Revenue	20,195	18,028
Operating Lease, Lease Income, Total	29,442	26,416
Related Party [Member] | Fixed Storageand Throughput Revenue [Member]
Revenue	18,883	14,531
Operating Lease, Lease Income, Total	0	0
Related Party [Member] | Fixed Lease Revenue [Member]
Revenue	0	0
Operating Lease, Lease Income, Total	27,142	24,547
Related Party [Member] | Variable Cost Recovery Revenue [Member]
Revenue	680	3,076
Operating Lease, Lease Income, Total	954	763
Related Party [Member] | Variable Throughput Revenue [Member]
Revenue	632	421
Operating Lease, Lease Income, Total	$ 1,346	$ 1,106