Impairment and other charges, net Cost of closed restaurants (Details) - USD ($) $ in Thousands		4 Months Ended
		Jan. 20, 2019		Jan. 21, 2018	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Gain (Loss) on Sale of Assets and Asset Impairment Charges				$ 500
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve		$ 2,961	[1],[2]		$ 3,534
Restructuring Charges		0
Restructuring Reserve, Accrual Adjustment	[3]	146
Payments for Restructuring		(1,179)
Facility Closing [Member] | Interest Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		460
Restaurant Closing Costs [Member]
Restructuring Cost and Reserve [Line Items]
Other Accrued Liabilities		$ 2,100
Weighted Average [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
RemainingLeaseCommitmentTerm		4

[1] The weighted average remaining lease term related to these commitments is approximately 4 years.

[2] This balance excludes $2.1 million of restaurant closing costs that are included in “Accrued liabilities” and “Other long-term liabilities” on our condensed consolidated balance sheets, which were initially recorded as losses on the sale of company-operated restaurants to franchisees.

[3] Adjustments relate primarily to revisions of certain sublease and cost assumptions. Our estimates related to our future lease obligations, primarily the sublease income we anticipate, are subject to a high degree of judgment and may differ from actual sublease income due to changes in economic conditions, desirability of the sites and other factors.