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Acquisitions - Additional Information (Detail) - USD ($)
6 Months Ended 12 Months Ended
Dec. 31, 2018
Jul. 13, 2019
Dec. 28, 2019
Jul. 11, 2020
Business Acquisition [Line Items]        
Payments to acquire certain assets and assume liabilities in cash   $ 86,659,000    
Goodwill     $ 181,035,000 $ 181,035,000
Martin's Super Markets [Member]        
Business Acquisition [Line Items]        
Payments to acquire certain assets and assume liabilities in cash $ 86,700,000      
Business combination, cash acquired 7,800,000      
Business combination, property and equipment acquired 55,000,000.0      
Business combination, Intangible assets acquired $ 23,900,000      
Amortization of intangible assets, period 7 years      
Goodwill $ 0      
Merger/acquisition and integration costs     $ 1,200,000  
Martin's Super Markets [Member] | Trade Names [Member]        
Business Acquisition [Line Items]        
Indefinite-lived intangible assets acquired 20,600,000      
Martin's Super Markets [Member] | Customer Lists [Member]        
Business Acquisition [Line Items]        
Indefinite-lived intangible assets acquired $ 3,100,000