v3.22.4
Employee Benefit Plans - Fair Value of Company's Pension Plans' Assets (Detail) - USD ($)
$ in Thousands
Dec. 31, 2022
Jan. 01, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value $ 17,043 $ 20,004
Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 17,043 20,004
Intermediate—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,849 3,412
Intermediate—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,849 3,412
Intermediate—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 2,754 4,424
Intermediate—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 2,754 4,424
Short-term—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 531 1,727
Short-term—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 531 1,727
Short-term—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 538 79
Short-term—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 538 79
International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 836 821
International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 836 821
U.S. Large cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,635 1,912
U.S. Large cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,635 1,912
U.S. Large cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 997 1,330
U.S. Large cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 997 1,330
U.S. Mid cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 630 750
U.S. Mid cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 630 750
U.S. Mid cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 439 526
U.S. Mid cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 439 526
U.S. Small cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 607 730
U.S. Small cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 607 730
U.S. Small cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 422 491
U.S. Small cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 422 491
International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 745 1,188
International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 745 1,188
Emerging Markets    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 740 374
Emerging Markets | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 740 374
Commodities Broad Basket    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 185 1,058
Commodities Broad Basket | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 185 1,058
Cash    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,135 1,182
Cash | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,135 1,182
Level 1    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 12,170 13,032
Level 1 | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 12,170 13,032
Level 1 | Intermediate—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,849 3,412
Level 1 | Intermediate—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,849 3,412
Level 1 | Intermediate—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | Intermediate—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | Short-term—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 531 1,727
Level 1 | Short-term—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 531 1,727
Level 1 | Short-term—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | Short-term—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Level 1 | U.S. Large cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,635 1,912
Level 1 | U.S. Large cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,635 1,912
Level 1 | U.S. Large cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 997 1,330
Level 1 | U.S. Large cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 997 1,330
Level 1 | U.S. Mid cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 630 750
Level 1 | U.S. Mid cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 630 750
Level 1 | U.S. Mid cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 439 526
Level 1 | U.S. Mid cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 439 526
Level 1 | U.S. Small cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 607 730
Level 1 | U.S. Small cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 607 730
Level 1 | U.S. Small cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 422 491
Level 1 | U.S. Small cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 422 491
Level 1 | International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 396
Level 1 | International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 396
Level 1 | Emerging Markets    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 740 374
Level 1 | Emerging Markets | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 740 374
Level 1 | Commodities Broad Basket    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 185 202
Level 1 | Commodities Broad Basket | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 185 202
Level 1 | Cash    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,135 1,182
Level 1 | Cash | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 1,135 1,182
Observable Inputs (Level 2)    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,873 6,972
Observable Inputs (Level 2) | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 4,873 6,972
Observable Inputs (Level 2) | Intermediate—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Intermediate—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Intermediate—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 2,754 4,424
Observable Inputs (Level 2) | Intermediate—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 2,754 4,424
Observable Inputs (Level 2) | Short-term—government    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Short-term—government | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Short-term—corporate    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 538 79
Observable Inputs (Level 2) | Short-term—corporate | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 538 79
Observable Inputs (Level 2) | International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 836 821
Observable Inputs (Level 2) | International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 836 821
Observable Inputs (Level 2) | U.S. Large cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Large cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Large cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Large cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Mid cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Mid cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Mid cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Mid cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Small cap value    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Small cap value | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Small cap growth    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | U.S. Small cap growth | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | International    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 745 792
Observable Inputs (Level 2) | International | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 745 792
Observable Inputs (Level 2) | Emerging Markets    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Emerging Markets | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Commodities Broad Basket    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 856
Observable Inputs (Level 2) | Commodities Broad Basket | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 856
Observable Inputs (Level 2) | Cash    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value 0 0
Observable Inputs (Level 2) | Cash | Summit Materials, LLC    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total fair value $ 0 $ 0