Stock Plans (Tables)

3 Months Ended

Mar. 31, 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 or released		(19,474	)	$	30.29
Cancelled or forfeited		(41,422	)	$	43.68
Balances - March 31, 2016		1,936,453		$	39.62		7.86	$	25,732
Vested and expected to vest - March 31, 2016		1,729,309		$	38.72		7.78	$	24,226
Exercisable - March 31, 2016		784,409		$	32.48		6.94	$	14,863

(1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the closing stock price of $50.50 of the Company’s common stock on March 31, 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		704,760		$	51.32
Granted, performance RSUs		273,900		$	51.55
Released		(261,627	)	$	41.73
Cancelled or expired		(61,460	)	$	47.19
Unvested - March 31, 2016		2,553,598		$	51.09

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 March 31
	2016		2015
Cost of revenue	$	1,393	$	914
Research and development		4,249		3,328
Sales and marketing		5,094		4,465
General and administrative		4,919		3,839
Total stock-based compensation expense	$	15,655	$	12,546

Weighted Average Assumptions for Fair Value of Stock Options Grants

The fair value of stock option grants for the three months ended March 31, 2016 and 2015 was estimated using the following weighted average assumptions:

	For the three months ended March 31
	2016			2015
Stock option grants:
Dividend rate		0	%		0	%
Risk-free interest rate		1.5	%		1.7	%
Expected term (in years)		6.1			6.1
Expected volatility		58	%		50	%