ACQUISITIONS, DISPOSTIONS, GOODWILL AND INTANGIBLES - Intangible Assets By Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023	Dec. 30, 2023
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (28,335)		$ (18,972)
Amortization expense	9,200	$ 900
Intangible Assets Excluding Intangible Assets Held for Sale
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	207,922		87,053
Accumulated Amortization	(28,335)		(18,972)
Net Carrying Amount	179,587		68,081
Operating permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,677		38,677
Accumulated Amortization	(6,089)		(5,691)
Net Carrying Amount	32,588		32,986
Mineral leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,375		17,778
Accumulated Amortization	(7,498)		(7,676)
Net Carrying Amount	9,877		10,102
Reserve rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	25,586		25,586
Accumulated Amortization	(5,226)		(5,020)
Net Carrying Amount	20,360		20,566
Intellectual property
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,400		0
Accumulated Amortization	(2,339)		0
Net Carrying Amount	19,061		0
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	104,884		5,012
Accumulated Amortization	(7,183)		(585)
Net Carrying Amount	97,701		4,427
Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	(28,335)		(18,972)
Amortization expense	9,200	$ 900
Summit Materials, LLC | Intangible Assets Excluding Intangible Assets Held for Sale
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	207,922		87,053
Accumulated Amortization	(28,335)		(18,972)
Net Carrying Amount	179,587		68,081
Summit Materials, LLC | Operating permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,677		38,677
Accumulated Amortization	(6,089)		(5,691)
Net Carrying Amount	32,588		32,986
Summit Materials, LLC | Mineral leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,375		17,778
Accumulated Amortization	(7,498)		(7,676)
Net Carrying Amount	9,877		10,102
Summit Materials, LLC | Reserve rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	25,586		25,586
Accumulated Amortization	(5,226)		(5,020)
Net Carrying Amount	20,360		20,566
Summit Materials, LLC | Intellectual property
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,400		0
Accumulated Amortization	(2,339)		0
Net Carrying Amount	19,061		0
Summit Materials, LLC | Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	104,884		5,012
Accumulated Amortization	(7,183)		(585)
Net Carrying Amount	$ 97,701		$ 4,427