Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary and Allocation of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense recorded for the periods presented and its allocation within the condensed consolidated statements of operations (in thousands):

	Three Months Ended				Nine Months Ended
	September 30, 2014		September 30, 2013		September 30, 2014		September 30, 2013
Cost of sales - product	$	668	$	686	$	1,828	$	2,252
Cost of sales - service		1,102		1,479		3,164		4,600
Stock-based compensation expense included in cost of sales		1,770		2,165		4,992		6,852
Sales and marketing		4,673		5,889		10,397		19,742
Research and development		3,203		3,669		7,304		12,578
General and administrative		5,122		5,479		11,485		14,128
Stock-based compensation expense included in operating      expenses		12,998		15,037		29,186		46,448
Stock-based compensation expense related to employee      equity awards and employee stock purchases		14,768		17,202		34,178		53,300
Tax benefit		3,016		7,960		6,778		24,663
Stock-based compensation expense related to employee      equity awards and employee stock purchases, net of tax	$	11,752	$	9,242	$	27,400	$	28,637

Significant Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan

The fair value of each employee stock purchase right grant is estimated on the date of grant using the Black-Scholes option valuation model and is recognized as expense using the graded vesting method using the following assumptions:

	Three Months Ended		Nine Months Ended
	September 30, 2014	September 30, 2013	September 30, 2014		September 30, 2013
Expected volatility	26.47-32.18%	42.40-48.89%	26.47-42.11%		42.40-50.55%
Risk-free interest rate	0.05-0.47%	0.08-0.35%	0.05-0.47%		0.08-0.35%
Expected dividends	0.0%	0.0%		0.0%		0.0%
Expected life (yrs)	0.5-2.0	0.5-2.0	0.5-2.0		0.5-2.0