Share-based compensation plans (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

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

The following tables show the detail of share-based compensation by line item in the consolidated statements of operations as well as by grant type, for the years ended December 31, 2014, 2013 and 2012 and the assumptions for each of these years in which grants were awarded:

(U.S. Dollars in thousands, except assumptions)	Year Ended December 31, 2014		Year Ended December 31, 2013		Year Ended December 31, 2012
Cost of sales	$	137	$	104	$	592
Sales and marketing		1,701		1,444		1,550
General and administrative		3,578		4,483		4,023
Research and development		308		236		138
Total	$	5,724	$	6,267	$	6,303

Schedule of Share-based Payment Award, Valuation Assumptions

Assumptions:

Year Ended

December 31,

2014

Year Ended

December 31,

2013

Year Ended

December 31,

2012

Expected term

5.00 years

4.50 years

Expected volatility

31.7% – 34.5%

32.1% – 50.8%

50.9% – 51.8%

Risk free interest rate

1.52% – 1.70%

0.58% – 1.52%

0.76% – 0.84%

Dividend rate

—

Weighted average fair value of options granted

during the year

10.45

10.83

16.99

Schedule of Stock Option Activity

Summaries of the status of the Company’s stock option plans as of December 31, 2014 and 2013 and changes during the year ended December 31, 2014 are presented below:

	Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2013		1,924,179		$	33.12
Granted		286,750		$	33.20
Exercised		(366,958	)	$	26.05
Forfeited		(316,135	)	$	32.78
Outstanding at December 31, 2014		1,527,836		$	34.91		4.48
Vested and expected to vest at December 31, 2014		1,437,703		$	35.23		4.22
Options exercisable at December 31, 2014		936,561		$	36.64		2.72

Schedule of Stock Options Outstanding and Exercisable by Price Range

Outstanding and exercisable by price range as of December 31, 2014

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$10.42 – $21.78		164,750		7.00	$	21.11		47,565	$	20.41
$22.75 – $27.97		141,333		5.97	$	24.87		81,333	$	24.64
$27.98 – $31.40		151,500		5.23	$	29.27		119,000	$	29.34
$31.83 – $36.25		238,425		8.24	$	34.25		44,000	$	31.83
$37.36 – $37.36		53,334		5.27	$	37.36		41,334	$	37.36
$38.11 – $38.11		142,075		1.22	$	38.11		142,075	$	38.11
$38.82 – $39.94		299,687		3.44	$	39.32		137,021	$	39.83
$40.27 – $41.37		157,500		1.82	$	41.18		145,001	$	41.16
$43.04 – $44.97		160,732		1.74	$	44.61		160,732	$	44.61
$45.84 – $50.99		18,500		1.92	$	48.43		18,500	$	48.43
$10.42 – $50.99		1,527,836		4.48	$	34.91		936,561	$	36.64

Schedule of Changes in Restricted Stock

A summary of the status of our restricted stock as of December 31, 2014 and 2013 and changes during the year ended December 31, 2013 are presented below:

	Shares			Weighted Average Grant Date Fair Value
Non-vested as of December 31, 2013		286,704		$	28.01
Granted		358,450		$	33.56
Vested		(84,396	)	$	29.25
Cancelled		(99,782	)	$	(30.39	)
Non-vested as of December 31, 2014		460,976		$	31.55