Unaudited Consolidated Statements of Changes in Stockholders’ Equity - Summit Materials Inc - USD ($) $ in Thousands	Total	Common Class A	Common Class B	Accumulated Earnings	Accumulated Other Comprehensive Income	Common Stock Common Class A	Common Stock Common Class B	Additional Paid-in Capital	Noncontrolling Interest
Beginning balance at Jan. 01, 2022	$ 1,823,212			$ 478,956	$ 7,083	$ 1,188	$ 0	$ 1,326,340	$ 9,645
Beginning balance (in shares) at Jan. 01, 2022		120,684,322				118,705,108	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(34,800)			(34,292)					(508)
Other comprehensive income, net of tax	1,325				1,306				19
Stock option exercises (in shares)						1,589
Stock option exercises	27					$ 0		27
Share-based compensation	5,422							5,422
Shares redeemed to settle taxes and other (in shares)						842,029
Shares redeemed to settle taxes and other	(1,180)					$ 8		(1,120)	(68)
Ending balance at Apr. 02, 2022	1,746,497			397,170	8,389	$ 1,181	$ 0	1,330,548	9,209
Ending balance (in shares) at Apr. 02, 2022						118,041,848	99
Beginning balance at Jan. 01, 2022	1,823,212			478,956	7,083	$ 1,188	$ 0	1,326,340	9,645
Beginning balance (in shares) at Jan. 01, 2022		120,684,322				118,705,108	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	157,966
Other comprehensive income, net of tax	(2,932)
Stock option exercises (in shares)		6,518
Repurchases of common stock	(47,509)			(47,494)		$ (15)		(121)	(121)
Repurchases of common stock, (in shares)		(1,506,878)				(1,506,878)
Shares redeemed to settle taxes and other (in shares)		909,864
Ending balance at Jul. 02, 2022	1,940,802			587,283	4,193	$ 1,182	$ 0	1,336,375	11,769
Ending balance (in shares) at Jul. 02, 2022		120,093,826				118,114,612	99
Beginning balance at Apr. 02, 2022	1,746,497			397,170	8,389	$ 1,181	$ 0	1,330,548	9,209
Beginning balance (in shares) at Apr. 02, 2022						118,041,848	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	192,766			190,113					2,653
Other comprehensive income, net of tax	(4,257)				(4,196)				(61)
Stock option exercises (in shares)						4,929
Stock option exercises	96					$ 0		96
Share-based compensation	4,734							4,734
Distributions from partnership	(25)								(25)
Shares redeemed to settle taxes and other (in shares)						67,835
Shares redeemed to settle taxes and other	991					$ 1		997	(7)
Ending balance at Jul. 02, 2022	1,940,802			587,283	4,193	$ 1,182	$ 0	1,336,375	11,769
Ending balance (in shares) at Jul. 02, 2022		120,093,826				118,114,612	99
Beginning balance at Dec. 31, 2022	2,011,990			590,895	3,084	$ 1,185	$ 0	1,404,122	12,704
Beginning balance (in shares) at Dec. 31, 2022		118,408,655	99			118,408,655	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(31,212)			(30,804)					(408)
LP Unit exchanges (in shares)						2,000
LP Unit exchanges	0					$ 0		21	(21)
Other comprehensive income, net of tax	164				161				3
Stock option exercises (in shares)						902
Stock option exercises	15							15
Share-based compensation	4,708							4,708
Shares redeemed to settle taxes and other (in shares)						407,114
Shares redeemed to settle taxes and other	(5,719)					$ 4		(5,680)	(43)
Ending balance at Apr. 01, 2023	1,979,946			560,091	3,245	$ 1,189	$ 0	1,403,186	12,235
Ending balance (in shares) at Apr. 01, 2023						118,818,671	99
Beginning balance at Dec. 31, 2022	2,011,990			590,895	3,084	$ 1,185	$ 0	1,404,122	12,704
Beginning balance (in shares) at Dec. 31, 2022		118,408,655	99			118,408,655	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	53,516
LP Unit exchanges (in shares)		2,000
Other comprehensive income, net of tax	3,287
Stock option exercises (in shares)		4,240
Shares redeemed to settle taxes and other (in shares)		471,379
Ending balance at Jul. 01, 2023	2,073,964			643,728	6,326	$ 1,190	$ 0	1,409,364	13,356
Ending balance (in shares) at Jul. 01, 2023		118,886,274	99			118,886,274	99
Beginning balance at Apr. 01, 2023	1,979,946			560,091	3,245	$ 1,189	$ 0	1,403,186	12,235
Beginning balance (in shares) at Apr. 01, 2023						118,818,671	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	84,728			83,637					1,091
Other comprehensive income, net of tax	3,123				3,081				42
Stock option exercises (in shares)						3,338
Stock option exercises	69							69
Share-based compensation	5,216							5,216
Shares redeemed to settle taxes and other (in shares)						64,265
Shares redeemed to settle taxes and other	882					$ 1		893	(12)
Ending balance at Jul. 01, 2023	$ 2,073,964			$ 643,728	$ 6,326	$ 1,190	$ 0	$ 1,409,364	$ 13,356
Ending balance (in shares) at Jul. 01, 2023		118,886,274	99			118,886,274	99