Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2015

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
	March 31, 2015		March 31, 2014
Cost of sales - product	$	955	$	640
Cost of sales - service		1,308		961
Stock-based compensation expense included in cost of sales		2,263		1,601
Sales and marketing		2,613		391
Research and development		2,573		1,042
General and administrative		1,783		2,613
Stock-based compensation expense included in operating      expenses		6,969		4,046
Stock-based compensation expense related to employee      equity awards and employee stock purchases		9,232		5,647
Tax benefit		1,529		985
Stock-based compensation expense related to employee      equity awards and employee stock purchases, net of tax	$	7,703	$	4,662

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
	March 31, 2015	March 31, 2014
Expected volatility	30.04-30.73%	32.30-42.11%
Risk-free interest rate	0.07-0.49%	0.07-0.30%
Expected dividends	0.0%	0.0%
Expected life (years)	0.5-2.0	0.5-2.0