Fair Value of Financial Instruments - Fair Value Measurements (Details) - Level 3 - USD ($) $ in Thousands	Jan. 02, 2021	Dec. 28, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	$ 654	$ 1,967
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	1,209	1,302
Summit Materials, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	654	1,967
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	$ 1,209	$ 1,302