Fair Values - Schedule of financial assets and liabilities measured at fair value (Details) - Recurring - USD ($) $ in Thousands		Oct. 03, 2020	Sep. 28, 2019
Prepaid expenses and other assets | (Level 1) | Supplemental Employee Retirement Plans, Defined Benefit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market fund Deferred comp and supplemental plan, fair value	[1]	$ 203	$ 433
Mutual funds, deferred benefit plan	[1]	22,778	22,419
Prepaid expenses and other assets | (Level 2) | Supplemental Employee Retirement Plans, Defined Benefit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market fund Deferred comp and supplemental plan, fair value	[1]	0	0
Mutual funds, deferred benefit plan	[1]	0	0
Prepaid expenses and other assets | Aggregate Fair Value | Supplemental Employee Retirement Plans, Defined Benefit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market fund Deferred comp and supplemental plan, fair value	[1]	203	433
Mutual funds, deferred benefit plan	[1]	22,778	22,419
Assets | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		115,818	44,274
Assets | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		36,158	490
Assets | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		151,976	44,764
Other current liabilities | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		115,818	44,274
Other current liabilities | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		33,347	(470)
Other current liabilities | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure		149,165	43,804
Money market fund deposits | Cash equivalents | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents		36,646	21,422
Money market fund deposits | Cash equivalents | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents		0	0
Money market fund deposits | Cash equivalents | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents		36,646	21,422
Certificates of deposit | Cash equivalents | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents		56,191
Certificates of deposit | Cash equivalents | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents		56,191
U.S. Treasury and agency obligations | Short-term investments | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	[2]	0	0
U.S. Treasury and agency obligations | Short-term investments | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	[2]	35,346	120
U.S. Treasury and agency obligations | Short-term investments | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	[2]	35,346	120
Foreign exchange contracts | Prepaid expenses and other assets | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	0	0
Foreign exchange contracts | Prepaid expenses and other assets | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	812	370
Foreign exchange contracts | Prepaid expenses and other assets | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	812	370
Foreign exchange contracts | Other current liabilities | (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	0	0
Foreign exchange contracts | Other current liabilities | (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	(2,811)	(960)
Foreign exchange contracts | Other current liabilities | Aggregate Fair Value
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative, fair value, net	[3]	$ (2,811)	$ (960)

[1] The fair value of mutual funds is determined based on quoted market prices. Securities traded on a national exchange are stated at the last reported sales price on the day of valuation; other securities traded in over-the-counter markets and listed securities for which no sale was reported on that date are stated as the last quoted bid price.

[2] Valuations are based upon quoted market prices in active markets involving similar assets. The market inputs used to value these instruments generally consist of market yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources include industry standard data providers, security master files from large financial institutions, and other third party sources which are input into a distribution-curve-based algorithm to determine a daily market value. This creates a "consensus price" or a weighted average price for each security.

[3] The principal market in which we execute our foreign currency contracts is the institutional market in an over-the-counter environment with a relatively high level of price transparency. The market participants usually are large commercial banks. Our foreign currency contracts' valuation inputs are based on quoted prices and quoted pricing intervals from public data sources and do not involve management judgment. See Note 7, "Derivative Instruments and Hedging Activities."