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Accrued Mining and Landfill Reclamation - Activity for Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
12 Months Ended
Jan. 02, 2021
Dec. 28, 2019
Dec. 29, 2018
Asset Retirement Obligation, Activity      
Beginning balance $ 36,676 $ 30,999  
Acquired obligations 861 805  
Change in cost estimate 6,523 4,468  
Settlement of reclamation obligations (3,095) (1,812)  
Accretion expense 2,638 2,216 $ 1,605
Ending balance 43,603 36,676 30,999
Summit Materials, LLC      
Asset Retirement Obligation, Activity      
Beginning balance 36,676 30,999  
Acquired obligations 861 805  
Change in cost estimate 6,523 4,468  
Settlement of reclamation obligations (3,095) (1,812)  
Accretion expense 2,638 2,216 1,605
Ending balance $ 43,603 $ 36,676 $ 30,999