Income Taxes - Narrative (Details)		4 Months Ended		12 Months Ended
		Jan. 20, 2019	Jan. 21, 2018	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		25.80%	28.60%	24.50%
Effective tax rates	[1]	23.10%	78.50%

[1] Percentages may not add due to rounding.