ACQUISITIONS, DISPOSTIONS, GOODWILL AND INTANGIBLES - Intangible Assets By Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2023	Jul. 02, 2022	Jul. 01, 2023	Jul. 02, 2022	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (17,321)		$ (17,321)		$ (15,503)
Amortization expense	900	$ 800	1,800	$ 1,800
Intangible Assets Excluding Intangible Assets Held for Sale
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	87,035		87,035		86,887
Accumulated Amortization	(17,321)		(17,321)		(15,503)
Net Carrying Amount	69,714		69,714		71,384
Operating permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,677		38,677		38,677
Accumulated Amortization	(4,926)		(4,926)		(4,109)
Net Carrying Amount	33,751		33,751		34,568
Mineral leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,778		17,778		18,091
Accumulated Amortization	(7,228)		(7,228)		(7,056)
Net Carrying Amount	10,550		10,550		11,035
Reserve rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	25,586		25,586		25,242
Accumulated Amortization	(4,608)		(4,608)		(3,872)
Net Carrying Amount	20,978		20,978		21,370
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,994		4,994		4,877
Accumulated Amortization	(559)		(559)		(466)
Net Carrying Amount	4,435		4,435		4,411
Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	(17,321)		(17,321)		(15,503)
Amortization expense	900	$ 800	1,800	$ 1,800
Summit Materials, LLC | Intangible Assets Excluding Intangible Assets Held for Sale
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	87,035		87,035		86,887
Accumulated Amortization	(17,321)		(17,321)		(15,503)
Net Carrying Amount	69,714		69,714		71,384
Summit Materials, LLC | Operating permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,677		38,677		38,677
Accumulated Amortization	(4,926)		(4,926)		(4,109)
Net Carrying Amount	33,751		33,751		34,568
Summit Materials, LLC | Mineral leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,778		17,778		18,091
Accumulated Amortization	(7,228)		(7,228)		(7,056)
Net Carrying Amount	10,550		10,550		11,035
Summit Materials, LLC | Reserve rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	25,586		25,586		25,242
Accumulated Amortization	(4,608)		(4,608)		(3,872)
Net Carrying Amount	20,978		20,978		21,370
Summit Materials, LLC | Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,994		4,994		4,877
Accumulated Amortization	(559)		(559)		(466)
Net Carrying Amount	$ 4,435		$ 4,435		$ 4,411