Stock-Based Compensation (Tables)
 6 Months Ended
Mar. 28, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Stock-Based Compensation Expense in Consolidated Statements of Operations
The following presents stock-based compensation expense in the Company’s Consolidated Statements of Operations:
 
Three Months Ended
 
Six Months Ended
 
March 28,
2015
 
March 29,
2014
 
March 28,
2015
 
March 29,
2014
Cost of revenues
$
2.3

 
$
2.1

 
$
4.3

 
$
3.6

Research and development
2.2

 
2.2

 
4.1

 
4.1

Selling and marketing
2.3

 
2.4

 
4.3

 
4.1

General and administrative
6.9

 
5.7

 
13.0

 
9.5

Restructuring and divestiture
—

 
—

 
0.1

 
4.8

 
$
13.7

 
$
12.4

 
$
25.8

 
$
26.1
Weighted-Average Assumptions Utilized to Value Stock Options
The Company uses a binomial model to determine the fair value of its stock options. The weighted-average assumptions utilized to value these stock options are indicated in the following table:
 
 
Three Months Ended
 
Six Months Ended
 
March 28,
2015
 
March 29,
2014
 
March 28,
2015
 
March 29,
2014
Risk-free interest rate
1.7
%
 
1.3
%
 
1.7
%
 
1.2
%
Expected volatility
38.6
%
 
41.4
%
 
38.6
%
 
41.4
%
Expected life (in years)
5.3

 
4.5

 
5.3

 
4.4

Dividend yield
—

 
—

 
—

 
—

Weighted average fair value of options granted
$
10.36

 
$
7.82

 
$
9.55

 
$
7.65