GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Schedule of Condensed Consolidating Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2022	Oct. 02, 2021	Oct. 01, 2022	Oct. 02, 2021
Condensed Consolidating Statements of Operations
Revenue	$ 752,747	$ 717,240	$ 1,860,248	$ 1,813,001
Cost of revenue (excluding items shown separately below)	534,936	486,936	1,372,521	1,301,346
Depreciation, depletion, amortization and accretion	52,133	59,082	150,483	173,651
Operating income	127,062	125,017	204,003	195,881
Other income, net	(3,283)	(1,137)	(4,956)	(10,721)
(Gain) loss on sale of businesses	(4,115)	113	(174,373)	(15,319)
Income from operations before taxes	112,480	95,891	319,650	143,369
Income tax expense	24,829	20,513	74,033	33,478
Net income (loss) attributable to Summit Inc/LLC	86,489	74,204	242,310	108,346
Comprehensive income attributable to member of Summit Materials, LLC	78,826	71,008	231,757	108,813
Summit Materials, LLC
Condensed Consolidating Statements of Operations
Revenue	752,747	717,240	1,860,248	1,813,001
Cost of revenue (excluding items shown separately below)	534,936	486,936	1,372,521	1,301,346
General and administrative expenses	38,616	46,205	133,241	142,123
Depreciation, depletion, amortization and accretion	52,133	59,082	150,483	173,651
Operating income	127,062	125,017	204,003	195,881
Other income, net	(3,283)	(1,137)	(4,956)	(10,721)
Other (income) loss, net		4,879		(4,705)
Interest expense (income)	21,980	24,134	62,728	72,474
(Gain) loss on sale of businesses	(4,115)	113	(174,373)	(15,319)
Income from operations before taxes	112,480	95,891	320,604	143,431
Income tax expense	7,147	7,016	19,557	12,531
Net income (loss) attributable to Summit Inc/LLC	105,333	88,875	301,047	130,900
Comprehensive income attributable to member of Summit Materials, LLC	95,086	84,799	286,934	131,582
Summit Materials, LLC | Eliminations
Condensed Consolidating Statements of Operations
Revenue	(2,875)	(4,151)	(8,366)	(10,174)
Cost of revenue (excluding items shown separately below)	(2,875)	(4,151)	(8,366)	(10,174)
General and administrative expenses	0	0	0	0
Depreciation, depletion, amortization and accretion	0	0	0	0
Operating income	0	0	0	0
Other income, net	144,575		316,514
Other (income) loss, net		147,546		296,208
Interest expense (income)	0	0	0	0
(Gain) loss on sale of businesses	0	0	0	0
Income from operations before taxes	(144,575)	(147,546)	(316,514)	(296,208)
Income tax expense	0	0	0	0
Net income (loss) attributable to Summit Inc/LLC	(144,575)	(147,546)	(316,514)	(296,208)
Comprehensive income attributable to member of Summit Materials, LLC	(154,822)	(151,622)	(330,627)	(295,526)
Issuers | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	0	0	0	0
Cost of revenue (excluding items shown separately below)	0	0	0	0
General and administrative expenses	9,138	16,372	42,360	51,555
Depreciation, depletion, amortization and accretion	822	1,068	2,341	3,273
Operating income	(9,960)	(17,440)	(44,701)	(54,828)
Other income, net	(147,353)		(320,069)
Other (income) loss, net		(141,753)		(290,566)
Interest expense (income)	35,536	35,033	103,017	102,981
(Gain) loss on sale of businesses	(5,120)	0	(131,721)	0
Income from operations before taxes	106,977	89,280	304,072	132,757
Income tax expense	1,644	405	3,025	1,857
Net income (loss) attributable to Summit Inc/LLC	105,333	88,875	301,047	130,900
Comprehensive income attributable to member of Summit Materials, LLC	95,086	84,799	286,934	131,582
Guarantors  | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	718,510	686,736	1,770,642	1,735,193
Cost of revenue (excluding items shown separately below)	511,848	465,966	1,310,495	1,247,002
General and administrative expenses	27,717	28,373	85,816	87,968
Depreciation, depletion, amortization and accretion	48,442	55,081	139,280	161,783
Operating income	130,503	137,316	235,051	238,440
Other income, net	(399)		(1,384)
Other (income) loss, net		(1,044)		(9,784)
Interest expense (income)	(14,926)	(12,276)	(44,399)	(34,635)
(Gain) loss on sale of businesses	1,005	113	(42,652)	(15,319)
Income from operations before taxes	144,823	150,523	323,486	298,178
Income tax expense	4,119	5,634	13,985	8,314
Net income (loss) attributable to Summit Inc/LLC	140,704	144,889	309,501	289,864
Comprehensive income attributable to member of Summit Materials, LLC	140,704	144,889	309,501	289,864
Non-Guarantors | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	37,112	34,655	97,972	87,982
Cost of revenue (excluding items shown separately below)	25,963	25,121	70,392	64,518
General and administrative expenses	1,761	1,460	5,065	2,600
Depreciation, depletion, amortization and accretion	2,869	2,933	8,862	8,595
Operating income	6,519	5,141	13,653	12,269
Other income, net	(106)		(17)
Other (income) loss, net		130		(563)
Interest expense (income)	1,370	1,377	4,110	4,128
(Gain) loss on sale of businesses	0	0	0	0
Income from operations before taxes	5,255	3,634	9,560	8,704
Income tax expense	1,384	977	2,547	2,360
Net income (loss) attributable to Summit Inc/LLC	3,871	2,657	7,013	6,344
Comprehensive income attributable to member of Summit Materials, LLC	$ 14,118	$ 6,733	$ 21,126	$ 5,662