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Goodwill - Summary of Changes in Carrying Amount of Goodwill (Detail)
$ in Thousands
9 Months Ended
Sep. 26, 2015
USD ($)
Goodwill [Line Items]  
Beginning balance $ 419,270
Acquisitions 155,508
Foreign currency translation adjustments (6,942)
Ending balance 567,836
Summit Materials, LLC [Member]  
Goodwill [Line Items]  
Beginning balance 419,270
Acquisitions 155,508
Foreign currency translation adjustments (6,942)
Ending balance 567,836
West Region [Member]  
Goodwill [Line Items]  
Beginning balance 297,085
Acquisitions 4,579
Foreign currency translation adjustments (6,942)
Ending balance 294,722
West Region [Member] | Summit Materials, LLC [Member]  
Goodwill [Line Items]  
Beginning balance 297,085
Acquisitions 4,579
Foreign currency translation adjustments (6,942)
Ending balance 294,722
Central Region [Member]  
Goodwill [Line Items]  
Beginning balance 96,025
Acquisitions 150,929
Ending balance 246,954
Central Region [Member] | Summit Materials, LLC [Member]  
Goodwill [Line Items]  
Beginning balance 96,025
Acquisitions 150,929
Ending balance 246,954
East Region [Member]  
Goodwill [Line Items]  
Beginning balance 26,160
Ending balance 26,160
East Region [Member] | Summit Materials, LLC [Member]  
Goodwill [Line Items]  
Beginning balance 26,160
Ending balance $ 26,160