Share-based compensation

9 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-based compensation

10. Share-based compensation

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 September 30,				Nine Months Ended September 30,
(U.S. Dollars, in thousands)	2017		2016		2017		2016
Cost of sales	$	151	$	175	$	437	$	401
Sales and marketing		394		331		1,073		887
General and administrative		2,828		7,148		6,935		10,082
Research and development		259		488		679		784
	$	3,632	$	8,142	$	9,124	$	12,154

	Three Months Ended September 30,				Nine Months Ended September 30,
(U.S. Dollars, in thousands)	2017		2016		2017		2016
Stock options	$	684	$	425	$	1,802	$	1,367
Time-based restricted stock awards		1,552		1,840		4,083		4,278
Performance-based restricted stock awards		115		5,089		340		5,089
Performance-based and market-based restricted stock units		997		472		1,935		472
Stock purchase plan		284		316		964		948
	$	3,632	$	8,142	$	9,124	$	12,154

The decreases in share-based compensation expense of $4.5 million and $3.0 million, respectively, for the three and nine months ended September 30, 2017, as compared to the prior period were primarily attributable to certain performance-based awards that were first determined to be probable to vest during the third quarter of 2016, resulting in additional expense of $5.1 million during the third quarter of 2016.

During the three months ended September 30, 2017 and 2016, the Company issued 93,486 and 181,235 shares, respectively, of common stock related to stock purchase plan issuances, stock option exercises and the vesting of restricted stock awards. During the nine months ended September 30, 2017 and 2016, the Company issued 384,761 and 710,026 shares, respectively, of common stock related to stock purchase plan issuances, stock option exercises and the vesting of restricted stock awards.