Unaudited Consolidated Statements of Changes in Members' Interest - Summit Materials LLC - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 01, 2023	Apr. 01, 2023	Jul. 02, 2022	Apr. 02, 2022	Jul. 01, 2023	Jul. 02, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 84,728	$ (31,212)	$ 192,766	$ (34,800)	$ 53,516	$ 157,966
Other comprehensive (loss) income	3,123	164	(4,257)	1,325	3,287	(2,932)
Share-based compensation	5,216	4,708	4,734	5,422
Shares redeemed to settle taxes and other	882	(5,719)	991	(1,180)
Summit Materials, LLC
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	2,105,146	2,143,150	1,797,061	1,884,944	2,143,150	1,884,944
Net contributed capital	69	15	96	(47,482)
Net income	100,090	(37,211)	242,101	(46,387)	62,879	195,714
Other comprehensive (loss) income	3,902	203	(5,610)	1,744
Distributions			(25)
Share-based compensation	5,216	4,708	4,734	5,422
Shares redeemed to settle taxes and other	881	(5,719)	991	(1,180)
Ending balance	2,215,304	2,105,146	2,039,348	1,797,061	2,215,304	2,039,348
Members' equity | Summit Materials, LLC
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,424,282	1,425,278	1,464,619	1,507,859	1,425,278	1,507,859
Net contributed capital	69	15	96	(47,482)
Distributions			(25)
Share-based compensation	5,216	4,708	4,734	5,422
Shares redeemed to settle taxes and other	881	(5,719)	991	(1,180)
Ending balance	1,430,448	1,424,282	1,470,415	1,464,619	1,430,448	1,470,415
Accumulated earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	83,637	(30,804)	190,113	(34,292)
Accumulated earnings | Summit Materials, LLC
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	702,037	739,248	346,724	393,111	739,248	393,111
Net income	100,090	(37,211)	242,101	(46,387)
Ending balance	802,127	702,037	588,825	346,724	802,127	588,825
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive (loss) income	3,081	161	(4,196)	1,306
Accumulated other comprehensive loss | Summit Materials, LLC
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(21,173)	(21,376)	(14,282)	(16,026)	(21,376)	(16,026)
Other comprehensive (loss) income	3,902	203	(5,610)	1,744
Ending balance	$ (17,271)	$ (21,173)	$ (19,892)	$ (14,282)	$ (17,271)	$ (19,892)