Fair Value Measurement - Non-recurring Fair Value Measurements Related to Impaired Property and Equipment (Details) - USD ($)	12 Months Ended
	Aug. 26, 2020	Aug. 28, 2019	Aug. 29, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	$ 320,000	$ 41,000
Operating lease right-of-use assets	16,756,000		$ 27,191,000
Total Nonrecurring Fair Value Measurements - Total impairments	(10,193,000)	(5,603,000)
Property and equipment, net	100,599,000	121,743,000
Goodwill, carrying value	195,000	514,000
Property held for sale	11,249,000	16,488,000
Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	0
Continuing Operations | Company-owned restaurants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Operating lease right-of-use assets	5,700,000
Fair Value, Measurements, Nonrecurring | Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	514,000
Impairment of goodwill	320,000	41,000
Property held for sale	3,362,000	8,030,000
Property held for sale - Total impairments	14,000	124,000
Operating lease right-of-use assets	272,000
Operating lease right-of-use assets, Total Impairments	5,380,000
Total Nonrecurring Fair Value Measurements	4,115,000	9,764,000
Total Nonrecurring Fair Value Measurements - Total impairments	(10,545,000)	(5,792,000)
Goodwill, carrying value	300,000	600,000
Property held for sale	3,400,000	8,200,000
Fair Value, Measurements, Nonrecurring | Continuing Operations | Company-owned restaurants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment related to Company-owned restaurants	481,000	1,220,000
Impairment loss for property and equipment	4,831,000	5,627,000
Operating lease right-of-use assets	300,000
Operating lease right-of-use assets, Total Impairments	5,400,000
Property and equipment, net	5,300,000	7,200,000
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	0
Property held for sale	0	0
Operating lease right-of-use assets	0
Total Nonrecurring Fair Value Measurements	0	0
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Continuing Operations | Company-owned restaurants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment related to Company-owned restaurants	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2) | Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	0
Property held for sale	0	0
Operating lease right-of-use assets	0
Total Nonrecurring Fair Value Measurements	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2) | Continuing Operations | Company-owned restaurants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment related to Company-owned restaurants	0	0
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3) | Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	514,000
Property held for sale	3,362,000	8,030,000
Operating lease right-of-use assets	272,000
Total Nonrecurring Fair Value Measurements	4,115,000	9,764,000
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3) | Continuing Operations | Company-owned restaurants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment related to Company-owned restaurants	$ 481,000	$ 1,220,000