Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

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

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The Company used the Black-Scholes model to estimate the fair value of its Employee Stock Purchase Plan awards with the following weighted-average assumptions:

	Six Months Ended
	June 30, 2017		June 30, 2016
Expected volatility factor	0.29		0.41
Risk free interest rate	0.60	%	0.35	%
Expected dividend yield	0	%	0	%
Expected life (in years)	0.5		0.5

Schedule of Total Stock-based Compensation Recognized by Income Statement Classification

The detail of the total stock-based compensation recognized by income statement classification is as follows (in thousands):

	Three Months Ended				Six Months Ended
Income Statement Classifications	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Cost of services and maintenance revenues	$	815	$	542	$	1,407	$	1,036
Research and development	11,660		9,689		21,326		17,444
Sales, marketing and services	14,728		12,560		26,325		23,504
General and administrative	13,476		15,576		26,429		32,444
Total	$	40,679	$	38,367	$	75,487	$	74,428

Schedule of Assumptions Used to Value Nonvested Share Grants

The grant date fair value of the non-vested performance stock unit awards was determined through the use of a Monte Carlo simulation model, which utilized multiple input variables that determined the probability of satisfying the market condition requirements applicable to each award as follows:

	March 2017 Grant		March 2016 Grant		January 2016 Grant
Expected volatility factor	0.27-0.32		0.29 - 0.39		0.29 - 0.37
Risk free interest rate	1.48	%	0.91	%	1.10	%
Expected dividend yield	0	%	0	%	0	%