Note 14 - Segment and Geographic Distribution of Operations - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Revenue	$ 163,447	$ 89,953	$ 269,176	$ 173,457
Corporate expenses	161,607	110,112	274,646	219,917
Long-lived asset impairment credit	0	0	500	0
Affiliate credit loss impairment credit	0	1,000	0	1,000
Loss on asset dispositions, net	(1,297)	(932)	(1,090)	(2,880)
Operating income (loss)	1,840	(20,159)	(5,470)	(46,460)
Depreciation and amortization	31,766	28,549	58,423	58,276
Property Plant And Equipment Additions	4,151	665	5,380	1,861
Total Assets	1,282,735		1,282,735		$ 1,095,780
Vessel [Member]
Revenue	162,175	88,514	266,051	169,507
Product and Service, Other [Member]
Revenue	1,272	1,439	3,125	3,950
Operating Segments [Member]
Revenue	163,447	89,953	269,176	173,457
Gross Profit	19,046	(11,157)	21,532	(28,005)
Operating Segments [Member] | Product and Service, Other [Member]
Revenue	1,272	1,439	3,125	3,950
Gross Profit	790	858	2,282	2,302
Operating Segments [Member] | Americas [Member]
Depreciation and amortization	7,503	7,382	14,619	15,389
Property Plant And Equipment Additions	538	0	538	0
Total Assets	312,606		312,606		278,394
Operating Segments [Member] | Americas [Member] | Vessel [Member]
Revenue	37,520	23,481	65,964	49,705
Gross Profit	5,930	(4,940)	5,848	(6,591)
Operating Segments [Member] | Asia Pacific [Member]
Depreciation and amortization	2,080	1,199	2,929	2,436
Property Plant And Equipment Additions	19	(50)	19	(42)
Total Assets	141,841		141,841		28,564
Operating Segments [Member] | Asia Pacific [Member] | Vessel [Member]
Revenue	16,362	4,870	21,259	8,442
Gross Profit	(899)	1,722	1,274	1,667
Operating Segments [Member] | Middle East [Member]
Depreciation and amortization	6,421	5,322	11,827	10,965
Property Plant And Equipment Additions	2,048	0	2,072	0
Total Assets	209,336		209,336		154,723
Operating Segments [Member] | Middle East [Member] | Vessel [Member]
Revenue	28,396	20,758	48,614	41,600
Gross Profit	(307)	(1,456)	(2,190)	(3,254)
Operating Segments [Member] | Europe and Mediterranean [Member]
Depreciation and amortization	6,958	7,225	13,720	14,709
Property Plant And Equipment Additions	169	287	445	593
Total Assets	285,910		285,910		293,760
Operating Segments [Member] | Europe and Mediterranean [Member] | Vessel [Member]
Revenue	32,475	22,467	56,394	37,216
Gross Profit	4,262	(1,986)	1,833	(10,007)
Operating Segments [Member] | West Africa [Member]
Depreciation and amortization	8,002	6,580	13,743	13,150
Property Plant And Equipment Additions	340	59	690	554
Total Assets	293,536		293,536		223,988
Operating Segments [Member] | West Africa [Member] | Vessel [Member]
Revenue	47,422	16,938	73,820	32,544
Gross Profit	9,270	(5,355)	12,485	(12,122)
Corporate, Non-Segment [Member]
Corporate expenses	(15,909)	(9,070)	(26,412)	(16,575)
Depreciation and amortization	802	841	1,585	1,627
Property Plant And Equipment Additions	1,037	$ 369	1,616	$ 756
Total Assets	$ 39,506		$ 39,506		$ 116,351