General form of registration statement for all companies including face-amount certificate companies

Summary of Significant Accounting Policies (Details)

v3.8.0.1
Summary of Significant Accounting Policies (Details)
ft² in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Apr. 24, 2017
Sep. 28, 2017
ft²
state
facility
Sep. 28, 2017
ft²
state
segment
facility
Dec. 28, 2017
Dec. 29, 2016
ft²
state
segment
facility
Dec. 31, 2015
Dec. 25, 2014
Number of reportable segments | segment     1   1    
Number of states with facilities | state   20 20   17    
Fiscal year period         364 days 371 days 364 days
Fiscal quarter period   91 days          
Stock split conversion ratio 321.820            
Scenario, Forecast [Member]              
Fiscal year period       364 days      
Minimum              
Fiscal year period     364 days        
Maximum              
Fiscal year period     371 days        
Warehouse Format Store [Member]              
Number of stores   80 80   69    
Area of facility | ft²   73 73   72    
Small Format Store [Member]              
Number of stores   1 1   1