Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Weighted average assumptions used to estimate fair value of stock options granted and stock purchase rights under ESPP

The weighted average assumptions used to estimate the fair value of stock purchase rights under the ESPP are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2014		2013		2014		2013
ESPP
Volatility	43	%	57	%	46	%	57	%
Expected term (years)	1.3		1.7		1.3		1.6
Risk free interest rate	0.2	%	0.2	%	0.2	%	0.2	%
Expected dividend yield	—	%	—	%	—	%	—	%

Compensation costs included in statement of income for all stock-based compensation arrangements

The compensation cost that has been included in the Consolidated Statements of Operations for all stock-based compensation arrangements was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2014		2013		2014		2013
Sales, marketing and administrative expense	$	7,668	$	7,965	$	23,105	$	22,667
Research and development expense	471		448		1,417		1,239
Cost of goods sold	92		41		257		96
Total stock-based compensation expense	$	8,231	$	8,454	$	24,779	$	24,002

At September 30, 2014, there was $31.1 million of unamortized compensation expense for stock options, restricted stock units and performance-based restricted stock units to be recognized over a weighted average period of 1.7 years.