Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Sep. 24, 2016
Current [Abstract]
Federal		$ 7	$ 13	$ 7
State and local		473	446	581
Total current taxes		480	459	588
Deferred [Abstract]
Deferred benefit	$ (1,086)	(1,086)	0	0
Provision for income taxes - current and deferred		$ (606)	$ 459	$ 588