Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

Stock-Based Compensation Expense

This expense was allocated as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Cost of revenues	$	288	$	152	$	460	$	305
Operating expenses
Sales and marketing		482		472		1,024		954
Research and development		173		95		308		188
General and administrative		704		640		1,354		1,251
Total stock-based compensation expense	$	1,647	$	1,359	$	3,146	$	2,698

Stock Option Activity

Our stock option activity was as follows:

	Options (#)			Weighted Average Exercise Price ($/share)
Outstanding at December 31, 2014		1,085,463		$	26.53
Granted		177,864			67.37
Exercised		(157,569	)		15.20
Forfeited		(12,683	)		41.56
Outstanding at June 30, 2015		1,093,075			34.64

Weighted Average Fair Value Per Share of Options Granted, Assumptions

The weighted average fair value per share of options granted during the first six months of 2015 was $23.06 and this was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

Volatility	39.0	%
Dividend yield	0	%
Life (in years)	4.5
Risk-free interest rate	1.36%-1.40	%

Weighted Average Fair Value Per Share, Employee Stock Purchase Plan, Assumptions

The fair value was estimated based on the market price of our common stock at the beginning of each offering period and using the Black-Scholes option pricing model with the following weighted-average assumptions:

Volatility	32.0	%
Dividend yield	0	%
Life (in years)	0.50
Risk-free interest rate	0.12	%

Restricted Stock Units [Member]

Restricted Stock Units and Restricted Stock Awards

Our restricted stock units activity was as follows:

	Restricted Stock Units (#)			Weighted Average Grant Date Fair Value ($/share)
Outstanding at December 31, 2014		115,133		$	45.25
Granted		66,454			67.34
Vested and common stock issued		(37,537	)		40.86
Forfeited		(3,422	)		49.08
Outstanding at June 30, 2015		140,628			56.77

Restricted Stock Award [Member]

Restricted Stock Units and Restricted Stock Awards

Our restricted stock awards activity was as follows:

	Restricted Stock Awards (#)			Weighted Average Grant Date Fair Value ($/share)
Outstanding at December 31, 2014		1,338		$	51.74
Restricted common stock issued		4,110			67.37
Restrictions lapsed		(2,364	)		58.52
Forfeited		—			—
Outstanding at June 30, 2015		3,084			67.37