Shareholders' equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders Equity Note [Abstract]

Components of Changes in Accumulated Other Comprehensive Income (Loss)

The components of and changes in accumulated other comprehensive loss are as follows:

(U.S. Dollars, in thousands)	Currency Translation Adjustments			Derivatives			Debt Securities			Accumulated Other Comprehensive Loss
Balance at December 31, 2014	$	(482	)	$	100		$	—		$	(382	)
Other comprehensive income (loss)		(3,907	)		202			(3,348	)		(7,053	)
Income taxes		—			(74	)		1,277			1,203
Balance at December 31, 2015	$	(4,389	)	$	228		$	(2,071	)	$	(6,232	)
Other comprehensive loss		(726	)		(360	)		(1,744	)		(2,830	)
Income taxes		—			132			659			791
Reclassification adjustments to:
Other expense, net		—			—			2,727			2,727
Income taxes		—			—			(1,036	)		(1,036	)
Balance at December 31, 2016	$	(5,115	)	$	—		$	(1,465	)	$	(6,580	)