Derivative instruments (Tables)

12 Months Ended

Dec. 31, 2015

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Schedule of Fair Values of Derivative Instruments

The tables below disclose the types of derivative instruments the Company owns, the classifications and fair values of these instruments within the balance sheet, and the amount of gain (loss) recognized in other comprehensive income (loss) (“OCI”) or net income (loss).

(U.S. Dollars, in thousands)	Fair value:favorable (unfavorable)		Balance sheetlocation
As of December 31, 2015
Cross-currency swap	$	2,485	Prepaid expenses and other current assets
Warrants	$	321	Other long-term assets
As of December 31, 2014
Cross-currency swap	$	2,504	Other long-term assets
Warrants	$	321	Other long-term assets

Schedule of Gain (Loss) Recognized in Other Comprehensive Income (Loss)

	For the year ended December 31,
(U.S. Dollars in thousands)	2015		2014			2013
Cross-currency swap unrealized gain (loss), net of taxes	$	128	$	251		$	(278	)
Warrants unrealized loss, net of taxes	$	—	$	(3	)	$	(1	)