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