STOCKHOLDERS' EQUITY/MEMBERS' INTEREST - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023
Changes in each component of accumulated other comprehensive loss
Beginning balance	$ 2,316,580	$ 2,011,990
Ending balance	4,218,637	1,979,946
Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Beginning balance	2,355,005	2,143,150
Foreign currency translation adjustment, net of tax	(4,724)	203
Ending balance	4,243,753	2,105,146
Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	6,840	6,356
Ending balance	6,840	6,356
Change in retirement plans | Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Beginning balance	(120)	(762)
Ending balance	(120)	(762)
Foreign currency translation adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	435	(3,272)
Foreign currency translation adjustment, net of tax	(3,585)	161
Ending balance	(3,150)	(3,111)
Foreign currency translation adjustments | Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Beginning balance	(15,689)	(20,614)
Foreign currency translation adjustment, net of tax	(4,724)	203
Ending balance	(20,413)	(20,411)
Accumulated Other Comprehensive Income
Changes in each component of accumulated other comprehensive loss
Beginning balance	7,275	3,084
Foreign currency translation adjustment, net of tax	(3,585)	161
Ending balance	3,690	3,245
Accumulated Other Comprehensive Income | Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Beginning balance	(15,809)	(21,376)
Ending balance	$ (20,533)	$ (21,173)