Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 28, 2019	Dec. 30, 2017	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Income Tax Disclosure [Abstract]
Federal corporate income tax rate		35.00%	21.00%
Discrete deferred tax benefit	$ 496	$ 1,086	$ 496	$ 0	$ 1,086

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Name:	us-gaap_DeferredIncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration