Employee Benefit Plans - Weighted-Average Assumptions Used to Determine Benefit Obligations (Detail) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2022 |
Jan. 01, 2022 |
|
| Pension Benefits | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 5.16% | 2.63% |
| Expected long-term rate of return on plan assets, benefit obligation | 5.00% | 5.00% |
| Pension Benefits | Summit Materials, LLC | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 5.16% | 2.63% |
| Expected long-term rate of return on plan assets, benefit obligation | 5.00% | 5.00% |
| Healthcare & Life Ins | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 5.09% | 2.31% |
| Healthcare & Life Ins | Summit Materials, LLC | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 5.09% | 2.31% |