Share-based compensation (Tables)

3 Months Ended

Mar. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Share-Based Compensation by Line Item in Condensed Consolidated Statements of Operations

The following tables present the detail of share-based compensation by line item in the condensed consolidated statements of operations as well as by award type:

	Three Months Ended March 31,
(U.S. Dollars, in thousands)	2017		2016
Cost of sales	$	149	$	117
Sales and marketing		360		276
General and administrative		2,102		1,558
Research and development		205		148
	$	2,816	$	2,099

	Three Months Ended March 31,
(U.S. Dollars, in thousands)	2017		2016
Stock options	$	595	$	475
Time-based restricted stock awards		1,292		1,308
Performance-based restricted stock awards		112		—
Performance-based and market-based restricted stock units		466		—
Stock purchase plan		351		316
	$	2,816	$	2,099