Stock Plans (Tables)

9 Months Ended

Sep. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Option Activity under Plans and Related Information

The following table summarizes option activity under the Plans and related information:

	Options Outstanding					Weighted- Average Remaining
	Number of Shares			Weighted Average Exercise Price		Contractual Term (in years)		Aggregate Intrinsic Value (in thousands) (1)
Balances - January 1, 2016		1,949,089		$	39.27		8.09	$	47,480
Granted		48,260		$	53.59
Exercised		(164,233	)	$	29.72
Cancelled or forfeited		(151,215	)	$	46.46
Balances - September 30, 2016		1,681,901		$	39.36		7.34	$	25,899
Vested and expected to vest - September 30, 2016		1,539,544		$	39.24		7.26	$	24,647
Exercisable - September 30, 2016		888,151		$	35.74		6.66	$	16,756

(1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the closing stock price of $53.71 of the Company’s common stock on September 30, 2016.

Summary of RSU Activity Outstanding and Weighted-Average Grant Date Fair Value

The following table summarizes RSU activity under the Plans and related information:

	Number of Restricted Stock Units Outstanding			Weighted- Average Grant Date Fair Value
Unvested - January 1, 2016		1,898,025		$	49.53
Granted		929,168		$	49.62
Granted, performance RSUs		273,900		$	51.55
Released		(681,176	)	$	41.82
Cancelled or forfeited		(244,068	)	$	48.66
Unvested - September 30, 2016		2,175,849		$	52.37

Stock-Based Compensation Expense

The Company recognized stock-based compensation expense under the 2011 Stock Option and Incentive Plan, 2003 Stock Plan, Inducement Plans, 2011 Employee Stock Purchase Plan, and the Incapsula 2010 Share Incentive Plan in the condensed consolidated statements of operations as follows (in thousands):

	For the three months ended September 30				For the nine months ended September 30
	2016		2015		2016		2015
Cost of revenue	$	1,079	$	836	$	3,604	$	2,713
Research and development		3,380		3,311		11,431		10,122
Sales and marketing		4,405		3,314		17,182		12,824
General and administrative		4,113		4,201		13,519		13,142
Total stock-based compensation expense	$	12,977	$	11,662	$	45,736	$	38,801

Weighted Average Assumptions for Fair Value of Stock Options Grants and ESPP Grants

The Company did not issue stock option grants for the three months ended September 30, 2016. The fair value of stock option grants for the nine months ended September 30, 2016 and the three and nine months ended September 30, 2015 and ESPP grants for the nine months ended September 30, 2016 and 2015 was estimated using the following weighted average assumptions:

	For the three months ended September 30				For the nine months ended September 30
	2016	2015			2016			2015
Stock option grants:
Dividend rate	-		0	%		0	%		0	%
Risk-free interest rate	-		1.7	%		1.4	%		1.7	%
Expected term (in years)	-		6.1			6.0			6.1
Expected volatility	-		48	%		58	%		49	%
ESPP grants:
Dividend rate	-	-				0	%		0	%
Risk-free interest rate	-	-				0.4	%		0.1	%
Expected term (in years)	-	-				0.5			0.5
Expected volatility	-	-				58	%		64	%