Employee Stock Award and Benefit Plans (Tables)

12 Months Ended

Oct. 03, 2020

Share-based Payment Arrangement [Abstract]

Schedule of deferred compensation plans' investments and liabilities

These investments and the liability to the employees were as follows (in thousands):

	Fiscal year-end
	2020		2019
Cash surrender value of life insurance contracts	$	18,520	$	16,223
Fair value of mutual and money market funds	22,981		22,852
Total assets	$	41,501	$	39,075
Total assets, included in:
Prepaid expenses and other assets	$	1,781	$	3,233
Other assets	39,720		35,842
Total assets	$	41,501	$	39,075

	Fiscal year-end
	2020		2019
Total deferred compensation liability, included in:
Other current liabilities	$	1,781	$	3,233
Other long-term liabilities	42,854		39,715
Total deferred compensation liability	$	44,635	$	42,948

Schedule of weighted-average assumptions used to estimate fair value of stock options granted and shares purchased

The fair values of shares purchased under the employee stock purchase plan for fiscal 2020, 2019, and 2018 were estimated using the following weighted-average assumptions:

	Employee Stock Purchase Plans
	Fiscal
	2020			2019			2018
Expected life in years	0.5			0.5			0.5
Expected volatility	58.0		%	47.9		%	50.1		%
Risk-free interest rate	1.0		%	2.4		%	1.6		%
Weighted average fair value per share	$	43.54		$	40.77		$	64.39

Schedule of Share-based Payment Award, Restricted Stock Units, Valuation Assumptions

The weighted average fair value for the performance units was determined using a Monte Carlo simulation model incorporating the following weighted average assumptions: 

	Fiscal
	2020			2019			2018
Risk-free interest rate	0.8		%	2.9		%	1.7		%
Volatility	50.5		%	43.7		%	37.0		%
Weighted average fair value	$	161.46		$	117.43		$	315.05

Schedule of stock-based compensation expense

The following table shows total stock-based compensation expense and related tax benefits included in the Consolidated Statements of Operations for fiscal 2020, 2019, and 2018 (in thousands):

	Fiscal
	2020		2019		2018
Cost of sales	$	5,314	$	4,880	$	4,403
Research and development	4,478		2,990		3,247
Selling, general and administrative	34,995		28,596		25,088
Income tax benefit	(5,640)		(4,946)		(5,073)
	$	39,147	$	31,520	$	27,665

Schedule of restricted stock award and restricted stock unit activity

The following table summarizes the activity of our time-based and performance restricted stock units for fiscal 2020, 2019, and 2018 (in thousands, except per share amounts):

	Time Based Restricted Stock Units			Performance Restricted Stock Units
	Number of Shares	Weighted Average Grant Date Fair Value		Number of Shares	Weighted Average Grant Date Fair Value
Nonvested stock at September 30, 2017	399	$	118.83	176	$	105.34
Granted	99	254.20		78	315.05
Vested (1)	(213)	88.45		(95)	70.57
Forfeited	(6)	119.66		—	—
Nonvested stock at September 29, 2018	279	$	155.24	159	$	155.76
Granted	195	128.25		105	117.43
Vested(1)	(169)	127.90		(131)	74.48
Forfeited	(10)	170.97		—	—
Nonvested stock at September 28, 2019	295	$	152.47	133	$	184.26
Granted	284	141.05		84	152.96
Vested(1)	(150)	150.91		(81)	163.17
Forfeited	(10)	169.92		—	—
Nonvested stock at October 3, 2020	419	$	144.87	136	$	177.54

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(1)Service-based restricted stock units vested during each fiscal year. Performance-based restricted stock units included at 100% of target goal. Under the terms of the market-based awards, the recipient may earn between 0% and 200% of the award. Under the terms of the performance-based awards based on free cash flow targets, the recipient may earn between 0% and 100% of the award.