Note 15 - Segment Information, Geographical Data and Major Customers - Segment Reporting Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue	$ 1,352,786	$ 1,345,835	$ 1,009,985
Total vessel operating costs	680,582	693,107	556,515
General and Administrative Expense	134,531	110,817	95,283
Depreciation and amortization	262,339	242,770	180,331
Additions to properties and equipment	36,488	27,580	45,852
Total assets	2,386,911	2,074,904	2,062,774
Costs of other operating revenues	6,420	3,555	4,342
Corporate expenses	1,070,190	1,034,487	827,770
Gain on asset dispositions, net	13,682	15,762	8,701
Operating income	282,596	311,348	182,215
Operating Segments [Member]
Revenue	1,352,786	1,345,835	1,009,985
Crew costs	402,290	416,276	329,473
Repair and maintenance	103,903	98,376	78,716
Insurance	10,389	11,027	9,297
Fuel, lube and supplies	61,153	65,371	60,548
Other	102,847	102,057	78,481
Total vessel operating costs	680,582	693,107	556,515
General and Administrative Expense	61,002	56,131	51,850
Depreciation and amortization	258,582	239,676	178,110
Operating profit	346,200	353,366	219,168
Additions to properties and equipment	29,743	23,766	40,684
Total assets	1,820,225	1,875,706	1,869,843
Costs of other operating revenues	6,420	3,555	4,342
Operating Segments [Member] | Americas [Member]
Crew costs	82,155	87,545	86,328
Repair and maintenance	20,732	20,677	17,295
Insurance	2,032	2,034	1,891
Fuel, lube and supplies	10,035	13,635	13,175
Other	26,567	24,391	19,232
Total vessel operating costs	141,521	148,282	137,921
General and Administrative Expense	14,927	14,046	15,105
Depreciation and amortization	48,506	44,822	41,215
Operating profit	65,275	54,779	42,964
Additions to properties and equipment	2,870	5,980	2,916
Total assets	360,846	350,126	418,151
Operating Segments [Member] | Asia Pacific [Member]
Crew costs	74,040	88,968	41,940
Repair and maintenance	12,904	13,999	9,212
Insurance	1,161	1,197	794
Fuel, lube and supplies	7,889	8,834	5,251
Other	9,572	10,311	7,751
Total vessel operating costs	105,566	123,309	64,948
General and Administrative Expense	9,080	8,544	8,147
Depreciation and amortization	21,894	18,606	10,669
Operating profit	53,207	59,869	38,471
Additions to properties and equipment	2,587	2,157	7,839
Total assets	148,385	173,587	167,085
Operating Segments [Member] | Middle East [Member]
Crew costs	54,330	53,390	53,416
Repair and maintenance	19,070	17,595	16,187
Insurance	1,819	1,882	1,784
Fuel, lube and supplies	10,995	10,019	12,092
Other	18,061	24,076	17,127
Total vessel operating costs	104,275	106,962	100,606
General and Administrative Expense	11,208	11,320	9,254
Depreciation and amortization	33,174	30,135	26,566
Operating profit	23,916	3,770	(1,051)
Additions to properties and equipment	1,968	1,260	3,016
Total assets	207,208	180,286	191,927
Operating Segments [Member] | Europe and Mediterranean [Member]
Crew costs	116,489	109,178	78,613
Repair and maintenance	27,195	28,288	17,029
Insurance	2,868	3,171	2,218
Fuel, lube and supplies	12,020	14,650	11,697
Other	20,988	18,864	13,758
Total vessel operating costs	179,560	174,151	123,315
General and Administrative Expense	14,259	12,726	10,063
Depreciation and amortization	92,114	92,331	63,152
Operating profit	57,694	53,873	33,687
Additions to properties and equipment	3,520	11,069	7,320
Total assets	607,178	659,158	671,626
Operating Segments [Member] | West Africa [Member]
Crew costs	75,276	77,195	69,176
Repair and maintenance	24,002	17,817	18,993
Insurance	2,509	2,743	2,610
Fuel, lube and supplies	20,214	18,233	18,333
Other	27,659	24,415	20,613
Total vessel operating costs	149,660	140,403	129,725
General and Administrative Expense	11,528	9,495	9,281
Depreciation and amortization	62,894	53,782	36,508
Operating profit	138,673	176,432	98,447
Additions to properties and equipment	18,798	3,300	19,593
Total assets	496,608	512,549	421,054
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Additions to properties and equipment	6,745	3,814	5,168
Total assets	566,686	199,198	192,931
Corporate expenses	(77,286)	(57,780)	(45,654)
Vessel [Member]
Revenue	1,338,931	1,337,637	998,993
Vessel [Member] | Operating Segments [Member]
Revenue	1,338,931	1,337,637	998,993
Vessel [Member] | Operating Segments [Member] | Americas [Member]
Revenue	270,229	261,929	237,205
Vessel [Member] | Operating Segments [Member] | Asia Pacific [Member]
Revenue	189,747	210,328	122,235
Vessel [Member] | Operating Segments [Member] | Middle East [Member]
Revenue	172,573	152,187	135,375
Vessel [Member] | Operating Segments [Member] | Europe and Mediterranean [Member]
Revenue	343,627	333,081	230,217
Vessel [Member] | Operating Segments [Member] | West Africa [Member]
Revenue	362,755	380,112	273,961
Product and Service, Other [Member]
Revenue	13,855	8,198	10,992
Product and Service, Other [Member] | Operating Segments [Member]
Revenue	$ 13,855	$ 8,198	$ 10,992