Impairment of Long-Lived Assets, Store Closings, Discontinued Operations and Property Held for Sale (Details Textual)	3 Months Ended	12 Months Ended
	Nov. 18, 2009 restaurant	Aug. 29, 2018 USD ($) location property restaurant	Aug. 30, 2017 USD ($) properties location property restaurant	Aug. 31, 2016 USD ($) location property restaurant
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge		$ 8,917,000	$ 10,567,000	$ 1,442,000
Number of restaurants with assets impaired | location		21	17	4
Number of restaurants with goodwill impairment		3	6	1
Number of restaurants | properties			5
Number of restaurant closings | restaurant		15	10	4
Reserve for restaurant closings		$ 1,300,000	$ 482,000	$ 202,000
Net gain on disposition of property and equipment		5,357,000	1,804,000	684,000
Insurance proceeds		$ 2,070,000	$ 0	$ 0
Number of restaurants with retired assets | restaurant		8
Number of restaurants related to net gain on disposition of property and equipment | property		10	6	2
Asset carrying value		$ 138,287,000	$ 172,814,000
Pretax profit (loss) for disposal group		(1,200,000)	1,300,000	$ 2,200,000
Accrued lease termination expense		$ 2,000,000	$ 500,000
Company-owned restaurants
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants | restaurant		146	167	175
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants | property		1
Ground lease impairment		$ 0
Discontinued Operations | Company-owned restaurants
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset carrying value		$ 1,800,000
Fuddruckers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants reclassified to continuing operations | location		0
Luby's Cafeteria | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of cafeterias classified as discontinued operations | restaurant	24
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants | property		10
Discontinued Operations, Held-for-sale | Luby's Cafeteria | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants | restaurant		1
Disposal Group, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on disposition of property and equipment		$ (4,900,000)	$ (2,400,000)	$ (1,000,000)
Disposal Group, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | property		15	4
Property held for sale		$ 19,500,000	$ 3,400,000
Discontinued Operations, Abandonment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge		$ 1,300,000	$ 500,000	$ 200,000
Discontinued Operations, Abandonment | Fuddruckers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of restaurants | restaurant		17
Minimum | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected disposal period		1 year
Minimum | Newer Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Time span for which future cash flows are estimated		20 years
Minimum | Older Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Time span for which future cash flows are estimated		5 years
Maximum | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected disposal period		2 years
Maximum | Newer Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Time span for which future cash flows are estimated		25 years
Maximum | Older Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Time span for which future cash flows are estimated		10 years
Natural Disasters, Hurricane Harvey
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on disposition of property and equipment		$ 1,300,000
Insurance proceeds		$ 1,300,000