Stock-Based Compensation (Tables)

6 Months Ended

Mar. 31, 2018

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 Income:



	Three Months Ended				Six Months Ended
	March 31, 2018		April 1, 2017		March 31, 2018		April 1, 2017
Cost of revenues	$	2.5	$	3.6	$	4.7	$	6.4
Research and development	2.9		4.1		5.4		6.9
Selling and marketing	2.5		3.2		5.4		5.9
General and administrative	11.6		8.9		19.1		19.8
Restructuring	—		—		1.3		—
	$	19.5	$	19.8	$	35.9	$	39.0

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 31, 2018			April 1, 2017			March 31, 2018			April 1, 2017
Risk-free interest rate	2.1		%	1.8		%	2.1		%	1.8		%
Expected volatility	35.3		%	36.5		%	35.3		%	36.6		%
Expected life (in years)	4.7			4.7			4.7			4.7
Dividend yield	—			—			—			—
Weighted average fair value of options granted	$	12.53		$	13.44		$	12.98		$	12.28