Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Jan. 02, 2021	Dec. 28, 2019
Schedule Of Accrued Expenses [Line Items]
Interest	$ 21,860	$ 26,892
Payroll and benefits	46,026	29,356
Finance lease obligations	24,601	16,007
Insurance	18,355	14,968
Non-income taxes	15,669	7,666
Deferred asset purchase payments	9,749	3,525
Professional fees	828	902
Other	23,482	20,689
Total	160,570	120,005
Summit Materials, LLC
Schedule Of Accrued Expenses [Line Items]
Interest	21,860	26,892
Payroll and benefits	46,026	29,356
Finance lease obligations	24,601	16,007
Insurance	18,355	14,968
Non-income taxes	15,900	7,898
Deferred asset purchase payments	9,749	3,525
Professional fees	828	902
Other	23,482	20,689
Total	$ 160,801	$ 120,237