Accrued Mining and Landfill Reclamation - Narrative (Detail) - USD ($) $ in Millions |
Dec. 28, 2019 |
Dec. 29, 2018 |
---|---|---|
Asset Retirement Obligations [Line Items] | ||
Anticipated costs | $ 97.4 | $ 92.5 |
Accrued expenses | ||
Asset Retirement Obligations [Line Items] | ||
Asset retirement obligation, current | 7.9 | 4.1 |
Summit Materials, LLC | ||
Asset Retirement Obligations [Line Items] | ||
Anticipated costs | 97.4 | 92.5 |
Summit Materials, LLC | Accrued expenses | ||
Asset Retirement Obligations [Line Items] | ||
Asset retirement obligation, current | $ 7.9 | $ 4.1 |