Income Taxes - Narrative (Details) - USD ($) $ in Thousands		4 Months Ended		12 Months Ended
		Jan. 21, 2018	Jan. 22, 2017	Sep. 29, 2019	Sep. 30, 2018
Income Tax Contingency [Line Items]
Statutory income tax rate, percent		28.60%	38.60%
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)		$ 30,627	$ 0
Income tax expense (benefit), continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ 30,700
Effective tax rates	[1]	78.50%	38.70%
Forecast
Income Tax Contingency [Line Items]
Statutory income tax rate, percent				21.00%	24.50%
Qdoba
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)		$ 2,300

[1] (1)Percentages may not add due to rounding.