Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2014

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

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity

The table below summarizes the stock-based compensation recognized, common stock shares purchased by Company employees, and the average purchase price per share as part of the ESPP program during the years ended December 31, 2014, 2013, and 2012.



	Year Ended December 31,
	2014		2013		2012
Stock-based compensation expense	$	841	$	750	$	759
Common stock shares purchased by Company employees	254		216		224
Average purchase price per share	$	10.26	$	11.48	$	10.59

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

Stock-based compensation expense included in cost of goods sold and operating expenses for years ended December 31, 2014, 2013, and 2012 was as follows:



	Year Ended December 31,
	2014		2013		2012
Cost of goods sold	$	857	$	680	$	597
Operating expenses:
Research and development	770		486		1,336
Clinical and regulatory affairs	644		1,169		320
Marketing and sales	2,533		3,117		1,558
General and administrative	3,063		2,470		2,641
Total operating expenses	$	7,010	$	7,242	$	5,855

Total	$	7,867	$	7,922	$	6,452

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of stock options granted was estimated at the date of grant using the Black-Scholes option-pricing model. The following assumptions were used to determine fair value for the stock awards granted in the applicable year:



	Year Ended December 31,
	2014	2013	2012
Average expected option life (in years) (a)	5.5	5.6	6.0
Volatility (b)	54.0%	54.0%	55.8%
Risk-free interest rate (c)	1.8%	1.7%	1.0%
Dividend Yield (d)	—%	—%	—%
Weighted-average grant-date fair value per stock option	$6.22	$7.41	$6.90

(a) Determined by the historical stock option exercise behavior of the Company's employees (maximum term is 10

years).

(b) Measured using weekly price observations for a period equal to stock options' expected term.

(d) The Company has never paid cash dividends on its common stock and does not expect to declare any cash dividends.

Schedule of Share-based Compensation, Stock Options, Activity

Stock option activity during the year ended December 31, 2014 is as follows:



	Number of Stock Options	Weighted Average Exercise Price	Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding — January 1, 2014	4,370,826	$7.60
Granted	1,418,087	13.37
Exercised	(314,563)	5.65		(a)	$	2,622
Forfeited	(208,014)	12.16
Expired	(20,024)	13.84
Outstanding — December 31, 2014	5,246,312	$9.07	6.4	(b)	$	32,829
Vested and Expected to Vest — December 31, 2014	4,795,880	$8.65	6.2	(b)	$	31,978
Vested — December 31, 2014	3,070,114	$6.22	4.9	(b)	$	27,878

(a) Represents the total difference between the Company's stock price at the time of exercise and the stock option exercise price, multiplied by the number of options exercised.

(b) Represents the total difference between the Company's closing stock price on the last trading day of period reported on and the stock option exercise price, multiplied by the number of in-the-money options as of the period reported on. The amount of intrinsic value will change based on the fair market value of the Company's stock.

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range

The following table summarizes information regarding outstanding stock option grants as of December 31, 2014:



					Outstanding				Exercisable
Range of Exercise Prices					Granted Stock Options Outstanding	Weighted- Average Remaining Contractual Life (Years)	Weighted- Average Exercise Price		Granted Stock Options Exercisable	Weighted- Average Exercise Price
$	1.64	—	$	2.94	724,715	3.3	$	2.58	724,715	$	2.58
2.95		—	4.41		837,352	4.0	3.94		837,352	3.94
4.42		—	7.25		657,217	5.1	5.34		573,634	5.10
7.26		—	11.62		670,785	6.7	9.41		424,706	9.14
11.63		—	13.16		171,048	8.1	12.23		43,674	12.37
13.17		—	13.24		879,833	9.3	13.17		108,918	13.18
13.25		—	14.15		654,188	8.3	13.81		202,493	13.84
14.16		—	17.86		651,174	8.3	15.18		154,622	15.09
$	1.64	—	$	17.86	5,246,312	6.4	$	9.07	3,070,114	$	6.22

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table summarizes activity and related information for the Company's restricted stock awards:



	Number of Restricted Stock Awards(2)		Weighted Average Fair Value per Share at Grant Date		Grant Date Fair Value		Vest Date Fair Value(1)
Unvested as of December 31, 2013	947,594		$	10.54
Granted	306,119		13.25		$	4,056
Forfeited	(43,416	)	12.62
Vested	(537,990	)	10.39				$	7,619
Unvested as of December 31, 2014	672,307		$	11.76