Stockholders' Equity and Stock-Based Compensation (Tables)

12 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense in Consolidated Statement of Operations

The following presents stock-based compensation expense in the Company’s Consolidated Statements of Operations in fiscal 2017, 2016 and 2015:



	2017		2016		2015
Cost of revenues	$	10.7	$	10.5	$	8.7
Research and development	11.2		10.8		8.6
Selling and marketing	11.9		10.9		8.8
General and administrative	34.4		32.8		29.1
Restructuring and divestiture	—		0.4		4.1
	$	68.2	$	65.4	$	59.3

Information Pertaining to Stock Options Granted and Related Assumptions

Information pertaining to stock options granted during fiscal 2017, 2016 and 2015 and related assumptions are noted in the following table:



	Years ended
	September 30, 2017			September 24, 2016			September 26, 2015
Options granted (in millions)	1.0			1.1			1.3
Weighted-average exercise price	$	38.07		$	39.32		$	27.68
Weighted-average grant date fair value	$	12.33		$	12.91		$	9.95
Assumptions:
Risk-free interest rates	1.8		%	1.6		%	1.7		%
Expected life (in years)	4.7			4.7			5.3
Expected volatility	36.6		%	37.8		%	38.6		%
Dividend yield	—			—			—

Stock Option Activity

The following table summarizes all stock option activity under the Company’s stock option plans for the year ended September 30, 2017:



	Number of Shares (in millions)		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in Years)	Aggregate Intrinsic Value (in millions)
Options outstanding at September 24, 2016	6.1		$	25.37	4.9	$	80.1
Granted	1.0		38.07
Canceled/ forfeited	(0.2	)	30.59
Exercised	(1.4	)	23.25			$	25.9
Options outstanding at September 30, 2017	5.5		$	28.15	5.4	$	50.3
Options exercisable at September 30, 2017	2.6		$	23.31	3.6	$	34.8
Options vested and expected to vest at September 30, 2017 (1)	5.4		$	28.09	5.5	$	50.0


(1)	This represents the number of vested stock options as of September 30, 2017 plus the unvested outstanding options at September 30, 2017 expected to vest in the future, adjusted for estimated forfeitures.

Restricted Stock Unit Activity

A summary of the Company’s RSU activity during the year ended September 30, 2017 is presented below:



Non-vested Shares	Number of Shares (in millions)		Weighted-Average Grant-Date Fair Value
Non-vested at September 24, 2016	2.8		$	29.40
Granted	1.0		38.03
Vested	(1.2	)	27.43
Forfeited	(0.3	)	32.21
Non-vested at September 30, 2017	2.3		$	34.06

Black-Scholes Model Weighted Average Assumptions Used to Estimate Fair Value of Shares to Be Issued as of Grant Date

The Company uses the Black-Scholes model to estimate the fair value of shares to be issued as of the grant date using the following weighted average assumptions:



	September 30, 2017		September 24, 2016		September 26, 2015
Assumptions:
Risk-free interest rates	0.72	%	0.34	%	0.10	%
Expected life (in years)	0.5		0.5		0.5
Expected volatility	24.9	%	27.2	%	27.4	%
Dividend yield	—		—		—