GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Schedule of Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 30, 2024	Dec. 30, 2023	Apr. 01, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 498,110	$ 374,162
Restricted cash	0	800,000
Accounts receivable, net	454,650	287,252
Cost and estimated earnings in excess of billings	11,681	10,289
Inventories	338,501	241,350
Total current assets	1,344,961	1,732,124
Property, plant and equipment, net	4,417,355	1,976,820
Goodwill	1,990,482	1,224,861
Intangible assets, net	179,587	68,081
Operating lease right-of-use assets	89,251	36,553
Total assets	8,129,900	5,149,582
Current liabilities:
Current portion of debt	7,575	3,822
Current portion of acquisition-related liabilities	8,993	7,007
Accounts payable	290,914	123,621
Current operating lease liabilities	16,745	8,596
Billings in excess of costs and estimated earnings	6,005	8,228
Total current liabilities	522,008	322,965
Long-term debt	2,772,709	2,283,639
Acquisition-related liabilities	20,655	28,021
Noncurrent operating lease liabilities	78,618	33,230
Total liabilities	3,911,263	2,833,002
Total liabilities and members' interest	8,129,900	5,149,582
Summit Materials, LLC
Current assets:
Cash and cash equivalents	486,208	355,669
Restricted cash	0	800,000
Accounts receivable, net	454,799	287,252
Intercompany receivables	0	0
Cost and estimated earnings in excess of billings	11,681	10,289
Inventories	338,501	241,350
Other current assets	45,519	25,389
Total current assets	1,336,708	1,719,949
Property, plant and equipment, net	4,417,355	1,976,820
Goodwill	1,991,482	1,225,861
Intangible assets, net	179,587	68,081
Operating lease right-of-use assets	89,251	36,553
Other assets	230,895	185,265
Total assets	8,245,278	5,212,529
Current liabilities:
Current portion of debt	7,575	3,822
Current portion of acquisition-related liabilities	8,993	7,007
Accounts payable	290,914	123,621
Accrued expenses	189,934	172,934
Current operating lease liabilities	16,745	8,596
Intercompany payables	0	0
Billings in excess of costs and estimated earnings	6,005	8,228
Total current liabilities	520,166	324,208
Long-term debt	2,772,709	2,283,639
Acquisition-related liabilities	20,655	28,021
Noncurrent operating lease liabilities	78,618	33,230
Other noncurrent liabilities	609,377	188,426
Total liabilities	4,001,525	2,857,524
Total member's interest	4,243,753	2,355,005	$ 2,105,146	$ 2,143,150
Total liabilities and members' interest	8,245,278	5,212,529
Summit Materials, LLC | Eliminations
Current assets:
Cash and cash equivalents	(3,208)	(2,755)
Restricted cash		0
Accounts receivable, net	(23)	(23)
Intercompany receivables	(5,296,201)	(3,419,449)
Cost and estimated earnings in excess of billings	0	0
Inventories	0	0
Other current assets	0	0
Total current assets	(5,299,386)	(3,422,227)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Operating lease right-of-use assets	0	0
Other assets	(5,442,343)	(5,435,646)
Total assets	(10,741,729)	(8,857,873)
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	0	0
Accounts payable	(126)	(23)
Accrued expenses	(3,208)	(2,755)
Current operating lease liabilities	0	0
Intercompany payables	(5,296,052)	(3,419,449)
Billings in excess of costs and estimated earnings	0	0
Total current liabilities	(5,299,386)	(3,422,227)
Long-term debt	0	0
Acquisition-related liabilities	0	0
Noncurrent operating lease liabilities	0	0
Other noncurrent liabilities	(98,585)	(133,921)
Total liabilities	(5,397,971)	(3,556,148)
Total member's interest	(5,343,758)	(5,301,725)
Total liabilities and members' interest	(10,741,729)	(8,857,873)
Summit Materials, LLC | Issuers | Reportable Legal Entities
Current assets:
Cash and cash equivalents	444,621	310,410
Restricted cash		800,000
Accounts receivable, net	1,723	6,441
Intercompany receivables	2,962,527	1,087,570
Cost and estimated earnings in excess of billings	0	0
Inventories	0	0
Other current assets	6,675	11,480
Total current assets	3,415,546	2,215,901
Property, plant and equipment, net	43,770	35,812
Goodwill	0	0
Intangible assets, net	0	0
Operating lease right-of-use assets	8,539	3,749
Other assets	5,391,496	5,384,259
Total assets	8,859,351	7,639,721
Current liabilities:
Current portion of debt	7,575	3,822
Current portion of acquisition-related liabilities	0	0
Accounts payable	33,255	4,290
Accrued expenses	100,272	88,318
Current operating lease liabilities	1,329	804
Intercompany payables	1,418,021	2,890,124
Billings in excess of costs and estimated earnings	0	0
Total current liabilities	1,560,452	2,987,358
Long-term debt	2,772,709	2,283,639
Acquisition-related liabilities	0	0
Noncurrent operating lease liabilities	12,163	7,951
Other noncurrent liabilities	270,274	5,768
Total liabilities	4,615,598	5,284,716
Total member's interest	4,243,753	2,355,005
Total liabilities and members' interest	8,859,351	7,639,721
Summit Materials, LLC | Guarantors  | Reportable Legal Entities
Current assets:
Cash and cash equivalents	3,035	3,115
Restricted cash		0
Accounts receivable, net	433,440	255,836
Intercompany receivables	2,333,674	2,331,879
Cost and estimated earnings in excess of billings	10,722	9,228
Inventories	330,727	234,738
Other current assets	36,480	13,264
Total current assets	3,148,078	2,848,060
Property, plant and equipment, net	4,292,849	1,858,020
Goodwill	1,934,795	1,167,685
Intangible assets, net	175,298	63,655
Operating lease right-of-use assets	76,672	28,511
Other assets	280,725	235,719
Total assets	9,908,417	6,201,650
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	8,993	7,007
Accounts payable	249,732	111,061
Accrued expenses	90,021	82,065
Current operating lease liabilities	14,862	7,230
Intercompany payables	3,876,327	525,230
Billings in excess of costs and estimated earnings	5,495	7,280
Total current liabilities	4,245,430	739,873
Long-term debt	0	0
Acquisition-related liabilities	20,655	28,021
Noncurrent operating lease liabilities	63,140	21,587
Other noncurrent liabilities	318,398	196,759
Total liabilities	4,647,623	986,240
Total member's interest	5,260,794	5,215,410
Total liabilities and members' interest	9,908,417	6,201,650
Summit Materials, LLC | Non-Guarantors | Reportable Legal Entities
Current assets:
Cash and cash equivalents	41,760	44,899
Restricted cash		0
Accounts receivable, net	19,613	24,998
Intercompany receivables	0	0
Cost and estimated earnings in excess of billings	959	1,061
Inventories	7,774	6,612
Other current assets	2,364	645
Total current assets	72,470	78,215
Property, plant and equipment, net	80,736	82,988
Goodwill	56,687	58,176
Intangible assets, net	4,289	4,426
Operating lease right-of-use assets	4,040	4,293
Other assets	1,017	933
Total assets	219,239	229,031
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	0	0
Accounts payable	8,053	8,293
Accrued expenses	2,849	5,306
Current operating lease liabilities	554	562
Intercompany payables	1,704	4,095
Billings in excess of costs and estimated earnings	510	948
Total current liabilities	13,670	19,204
Long-term debt	0	0
Acquisition-related liabilities	0	0
Noncurrent operating lease liabilities	3,315	3,692
Other noncurrent liabilities	119,290	119,820
Total liabilities	136,275	142,716
Total member's interest	82,964	86,315
Total liabilities and members' interest	$ 219,239	$ 229,031