Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property Plant And Equipment [Abstract]

Schedule of Property Plant and Equipment

	December 31,
(U.S. Dollars, in thousands)	2012			2011
	(Restated)			(Restated)
Cost
Buildings	$	3,911		$	3,829
Plant, equipment and instrumentation		120,982			104,782
Furniture and fixtures		5,567			5,697
		130,460			114,308
Accumulated depreciation		(76,625	)		(68,171	)
	$	53,835		$	46,137