Note 10 - Operating Segment Information (Detail) - Operating Income (Loss) by Operating Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenue	$ 96,888	$ 87,435
Direct operating expenses	53,137	48,809
Drydock expense	8,560	6,196
General and administrative expenses	10,950	12,116
Depreciation and amortization expense	15,170	15,029
Operating income (loss)	9,071	6,434
Quarter Ended March 31, 2012
Gain on sale of assets		(1,149)
North Sea [Member]
Revenue	40,622	37,663
Direct operating expenses	23,197	20,020
Drydock expense	2,583	3,551
General and administrative expenses	3,304	3,667
Depreciation and amortization expense	5,094	4,761
Operating income (loss)	6,444	5,664
Southeast Asia [Member]
Revenue	9,738	14,225
Direct operating expenses	6,145	3,803
Drydock expense	3,106	2,290
General and administrative expenses	1,267	773
Depreciation and amortization expense	2,807	2,510
Operating income (loss)	(3,587)	4,849
Americas [Member]
Revenue	46,528	35,547
Direct operating expenses	23,795	24,986
Drydock expense	2,871	355
General and administrative expenses	2,442	2,601
Depreciation and amortization expense	6,673	7,178
Operating income (loss)	10,747	1,576
Quarter Ended March 31, 2012
Gain on sale of assets		(1,149)
Other [Member]
General and administrative expenses	3,937	5,075
Depreciation and amortization expense	596	580
Operating income (loss)	$ (4,533)	$ (5,655)