Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 28, 2019	Sep. 25, 2021	Sep. 26, 2020	Sep. 28, 2019
Current [Abstract]
Federal		$ 7	$ 4	$ 67
State and local		1,001	346	790
Total current taxes		1,008	350	857
Deferred [Abstract]
Deferred	$ (496)	102	(496)	0
Provision for income taxes - current and deferred		$ 1,110	$ (146)	$ 857