Property, plant and equipment

12 Months Ended

Dec. 31, 2015

Property Plant And Equipment [Abstract]

Property, plant and equipment

3. Property, plant and equipment

	December 31,
(U.S. Dollars in thousands)	2015			2014
Cost
Buildings	$	3,328		$	3,683
Plant, equipment and instrumentation		150,366			140,110
Furniture and fixtures		5,711			5,779
		159,405			149,572
Accumulated depreciation		(107,099	)		(101,023	)
	$	52,306		$	48,549

Included within plant, equipment and instrumentation is capitalized computer software of $7.6 million and $9.0 million net of accumulated amortization as of December 31, 2015 and 2014, respectively.  Amortization of computer software for the years ended December 31, 2015, 2014 and 2013 was $4.4 million, $3.0 million and $2.7 million, respectively.  

Total depreciation expense, for the years ended December 31, 2015, 2014 and 2013 was $19.2 million, $20.6 million and $20.0 million, respectively.