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Employee Benefit Plans - Fair Value of Company's Pension Plans' Assets (Detail) - USD ($)
$ in Thousands
Dec. 31, 2016
Jan. 02, 2016
Dec. 27, 2014
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value $ 18,395 $ 18,337  
Intermediate - Government [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,770 1,410  
Intermediate - Corporate [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,658 3,376  
Short Term - Government [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 912 390  
Short Term - Corporate [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 3,613 5,571  
U.S. Large Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,181 1,148  
U.S. Large Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,103 1,153  
U.S. Mid Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 577 557  
U.S. Mid Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 546 569  
U.S. Small Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 551 554  
U.S. Small Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 540 554  
Managed Futures [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 366    
International [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,099 1,118  
Emerging Markets [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 359    
Commodities Broad Basket [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 707    
Cash      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,094 1,592  
Precious Metals      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 319 345  
Pension Benefits      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 18,395 18,336 $ 18,872
Pension Benefits | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 18,395 18,336 $ 18,872
Pension Benefits | Intermediate - Government [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,770 1,410  
Pension Benefits | Intermediate - Corporate [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,658 3,376  
Pension Benefits | Short Term - Government [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 912 390  
Pension Benefits | Short Term - Corporate [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 3,613 5,571  
Pension Benefits | U.S. Large Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,181 1,148  
Pension Benefits | U.S. Large Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,103 1,153  
Pension Benefits | U.S. Mid Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 577 557  
Pension Benefits | U.S. Mid Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 546 569  
Pension Benefits | U.S. Small Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 551 554  
Pension Benefits | U.S. Small Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 540 554  
Pension Benefits | Managed Futures [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 366    
Pension Benefits | International [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,099 1,118  
Pension Benefits | Emerging Markets [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 359    
Pension Benefits | Commodities Broad Basket [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 707    
Pension Benefits | Cash | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,094 1,592  
Pension Benefits | Precious Metals | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 319 345  
Quoted Prices in Active Markets for Identical Assets (Level 1)      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 9,442 7,590  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,181 1,148  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,103 1,153  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 577 557  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 546 569  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small Cap Value [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 551 554  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small Cap Growth [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 540 554  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Managed Futures [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 366    
Quoted Prices in Active Markets for Identical Assets (Level 1) | International [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,099 1,118  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Emerging Markets [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 359    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodities Broad Basket [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 707    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,094 1,592  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Precious Metals      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 319 345  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 9,442 7,590  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Large Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,181 1,148  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Large Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,103 1,153  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Mid Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 577 557  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Mid Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 546 569  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Small Cap Value [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 551 554  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | U.S. Small Cap Growth [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 540 554  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Managed Futures [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 366    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | International [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,099 1,118  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Emerging Markets [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 359    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Commodities Broad Basket [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 707    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Cash | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,094 1,592  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits | Precious Metals | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 319 345  
Level 2      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 8,953 10,747  
Level 2 | Intermediate - Government [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,770 1,410  
Level 2 | Intermediate - Corporate [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,658 3,376  
Level 2 | Short Term - Government [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 912 390  
Level 2 | Short Term - Corporate [Member]      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 3,613 5,571  
Level 2 | Pension Benefits | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 8,953 10,747  
Level 2 | Pension Benefits | Intermediate - Government [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 1,770 1,410  
Level 2 | Pension Benefits | Intermediate - Corporate [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 2,658 3,376  
Level 2 | Pension Benefits | Short Term - Government [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value 912 390  
Level 2 | Pension Benefits | Short Term - Corporate [Member] | Summit Materials, LLC      
Pension Plans, Postretirement and Other Employee Benefits [Line Items]      
Total fair value $ 3,613 $ 5,571