Share - Based Compensation Plans (Tables)

12 Months Ended

Sep. 29, 2017

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

Effects of Stock-Based Compensation Expense Related to Stock-Based Awards to Employees and Nonemployees

The following table shows a summary of share-based compensation expense included in the Consolidated Statement of Operations during the periods presented (in thousands): 

	Fiscal Years
	2017		2016		2015
Cost of revenue	$	3,189	$	2,150	$	1,949
Research and development	10,565		6,568		5,447
Selling, general and administrative	22,581		18,236		12,039
Total	$	36,335	$	26,954	$	19,435

Summary of Stock Option Activity

A summary of stock option activity for fiscal year 2017 is as follows (in thousands, except per share amounts):

	Number of Shares		Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value
Options outstanding - September 30, 2016	1,048		$	23.18
Granted (1)	379		44.74
Exercised	(234	)	13.34
Forfeited, canceled or expired	(16	)	56.80
Options outstanding - September 29, 2017	1,177		$	31.61	4.99	16,445
Options vested and expected to vest - September 29, 2017	1,177		$	31.61	4.99	16,445
Options exercisable - September 29, 2017	397		$	23.00	4.16	9,701

Weighted Average Assumptions used for Calculating Fair Value of Stock Options Granted

The weighted average Monte Carlo input assumptions used for calculating the fair value of these market-based stock options are as follows:

	Fiscal Years
	2017		2016		2015
Risk-free interest rate	1.9	%	2.1	%	1.9	%
Expected term (years)	7		7		7
Expected volatility	32.3	%	36.5	%	37.4	%

The weighted average Black-Scholes input assumptions used for calculating the fair value of these performance-based stock options are as follows:

	Fiscal Years
	2016		2015
Risk-free interest rate	1.15	%	1.2	%
Expected term (years)	4		4
Expected volatility	31.8	%	36.2	%
Expected dividends	—	%	—	%

Summary of Restricted Stock Awards and Unit Activity

A summary of restricted stock awards and units activity for fiscal year 2017 is as follows (in thousands):

	Number of Shares		Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value
Issued and unvested - September 30, 2016	1,708		$	32.76	$	72,165
Granted (1)	1,276		37.92
Vested	(984	)	26.63
Forfeited, canceled or expired	(93	)	36.30
Issued and unvested shares - September 29, 2017	1,907		39.20		$	85,093