Note 8 - Operating Segment Information (Details) - Operating Income (Loss) by Operating Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Revenue	$ 119,600	$ 96,888
Direct operating expenses	56,299	53,137
Drydock expense	7,211	8,560
General and administrative expenses	14,489	10,950
Depreciation and amortization expense	18,357	15,170
Operating income	23,244	9,071
North Sea [Member]
Segment Reporting Information [Line Items]
Revenue	52,623	40,622
Direct operating expenses	26,729	23,197
Drydock expense	2,668	2,583
General and administrative expenses	3,492	3,304
Depreciation and amortization expense	7,823	5,094
Operating income	11,911	6,444
Southeast Asia [Member]
Segment Reporting Information [Line Items]
Revenue	18,304	9,738
Direct operating expenses	5,484	6,145
Drydock expense	1,553	3,106
General and administrative expenses	1,362	1,267
Depreciation and amortization expense	2,896	2,807
Operating income	7,009	(3,587)
Americas [Member]
Segment Reporting Information [Line Items]
Revenue	48,673	46,528
Direct operating expenses	24,086	23,795
Drydock expense	2,990	2,871
General and administrative expenses	3,117	2,442
Depreciation and amortization expense	6,806	6,673
Operating income	11,674	10,747
Other [Member]
Segment Reporting Information [Line Items]
General and administrative expenses	6,518	3,937
Depreciation and amortization expense	832	596
Operating income	$ (7,350)	$ (4,533)