Accumulated other comprehensive loss (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Components of Changes in Accumulated Other Comprehensive Income (Loss)

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

(U.S. Dollars, in thousands)	Currency Translation Adjustments			Debt Security		Accumulated Other Comprehensive Loss
Balance at December 31, 2017	$	(563	)	$	4,350	$	3,787
Other comprehensive income		697			—		697
Income taxes		—			—		—
Balance at March 31, 2018	$	134		$	4,350	$	4,484