Note 13 - Segment and Geographic Distribution of Operations - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue	$ 86,467	$ 119,765	$ 305,179	$ 367,772
Corporate expenses	(111,643)	(142,316)	(466,633)	(404,337)
Long-lived asset impairments	(1,945)	(5,224)	(67,634)	(5,224)
Affiliate credit loss impairment expense	0	0	(53,581)	0
Affiliate guarantee obligation	0	0	(2,000)	0
Gain on asset dispositions, net	520	270	7,511	1,047
Operating loss	(25,176)	(22,551)	(161,454)	(36,565)
Depreciation and amortization	30,777	25,735	86,028	73,705
Additions to properties and equipment	607	5,083	4,682	13,931
Operating Segments [Member]
Revenue	86,467	119,765	305,179	367,772
Operating profit (loss)	(15,313)	1,477	(18,360)	14,108
Corporate, Non-Segment [Member]
Corporate expenses	(8,438)	(19,074)	(27,390)	(46,496)
Depreciation and amortization	791	350	2,535	1,046
Additions to properties and equipment	636	1,632	1,924	3,396
Americas [Member] | Operating Segments [Member]
Depreciation and amortization	8,076	6,929	23,645	19,706
Reductions to Properties and Equipment	(10)		(10)
Additions to properties and equipment		326		967
Middle East and Asia Pacific [Member] | Operating Segments [Member]
Depreciation and amortization	6,332	5,685	17,504	15,454
Additions to properties and equipment	5	594	1,188	4,231
Europe and Mediterranean [Member] | Operating Segments [Member]
Depreciation and amortization	8,248	7,436	21,860	22,623
Reductions to Properties and Equipment	(13)
Additions to properties and equipment		1,847	913	3,070
West Africa [Member] | Operating Segments [Member]
Depreciation and amortization	7,330	5,335	20,484	14,876
Reductions to Properties and Equipment	(11)
Additions to properties and equipment		684	667	2,267
Vessel [Member]
Revenue	85,395	117,173	298,344	360,476
Vessel [Member] | Americas [Member] | Operating Segments [Member]
Revenue	28,705	33,147	94,608	103,624
Operating profit (loss)	107	(168)	3,448	1,702
Vessel [Member] | Middle East and Asia Pacific [Member] | Operating Segments [Member]
Revenue	23,280	22,765	72,091	63,670
Operating profit (loss)	(2,222)	(809)	(2,479)	(4,098)
Vessel [Member] | Europe and Mediterranean [Member] | Operating Segments [Member]
Revenue	17,716	30,946	67,827	94,531
Operating profit (loss)	(3,883)	(276)	(4,086)	(768)
Vessel [Member] | West Africa [Member] | Operating Segments [Member]
Revenue	15,694	30,315	63,818	98,651
Operating profit (loss)	(10,168)	678	(19,015)	11,891
Product and Service, Other [Member]
Revenue	1,072	2,592	6,835	7,296
Product and Service, Other [Member] | Operating Segments [Member]
Revenue	1,072	2,592	6,835	7,296
Operating profit (loss)	$ 853	$ 2,052	$ 3,772	$ 5,381