LEASES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023	Dec. 30, 2023
Lease, Cost [Abstract]
Operating lease cost	$ 6,029	$ 2,641
Variable lease cost	1,665	30
Short-term lease cost	9,322	7,270
Financing lease cost:
Amortization of right-of-use assets	1,459	818
Interest on lease liabilities	645	148
Total lease cost	19,120	10,907
Operating leases:
Operating lease right-of-use assets	89,251		$ 36,553
Current operating lease liabilities	16,745		8,596
Noncurrent operating lease liabilities	78,618		33,230
Total operating lease liabilities	95,363		41,826
Finance leases:
Property and equipment, gross	53,619		30,136
Less accumulated depreciation	$ (11,715)		$ (12,088)
Finance lease, right-of-use asset, statement of financial position [Extensible List]	Property, plant and equipment, net		Property, plant and equipment, net
Property and equipment, net	$ 41,904		$ 18,048
Finance lease, liability, current, statement of financial position [Extensible Enumeration]	Accrued expenses		Accrued expenses
Current finance lease liabilities	$ 4,698		$ 4,020
Finance lease, liability, noncurrent, statement of financial position [Extensible Enumeration]	Other noncurrent liabilities		Other noncurrent liabilities
Long-term finance lease liabilities	$ 32,189		$ 14,357
Total finance lease liabilities	$ 36,887		$ 18,377
Weighted average remaining lease term (years):
Operating leases	7 years 8 months 12 days		8 years 4 months 24 days
Finance lease	10 years 7 months 6 days		6 years
Weighted average discount rate:
Operating leases	7.10%		5.10%
Finance leases	8.10%		7.70%
Operating Leases
2024 (nine months)	$ 17,288
2025	20,808
2026	17,554
2027	14,089
2028	10,906
2029	9,407
Thereafter	33,031
Total lease payments	123,083
Less imputed interest	(27,720)
Present value of lease payments	95,363		$ 41,826
Finance Leases
2024 (nine months)	5,734
2025	6,570
2026	5,072
2027	4,870
2028	4,627
2029	4,477
Thereafter	24,743
Total lease payments	56,093
Less imputed interest	(19,206)
Present value of lease payments	36,887		18,377
Summit Materials, LLC
Lease, Cost [Abstract]
Operating lease cost	6,029	2,641
Variable lease cost	1,665	30
Short-term lease cost	9,322	7,270
Financing lease cost:
Amortization of right-of-use assets	1,459	818
Interest on lease liabilities	645	148
Total lease cost	19,120	$ 10,907
Operating leases:
Operating lease right-of-use assets	89,251		36,553
Current operating lease liabilities	16,745		8,596
Noncurrent operating lease liabilities	78,618		33,230
Total operating lease liabilities	95,363		41,826
Finance leases:
Property and equipment, gross	53,619		30,136
Less accumulated depreciation	$ (11,715)		$ (12,088)
Finance lease, right-of-use asset, statement of financial position [Extensible List]	Property, plant and equipment, net		Property, plant and equipment, net
Property and equipment, net	$ 41,904		$ 18,048
Finance lease, liability, current, statement of financial position [Extensible Enumeration]	Accrued expenses		Accrued expenses
Current finance lease liabilities	$ 4,698		$ 4,020
Finance lease, liability, noncurrent, statement of financial position [Extensible Enumeration]	Other noncurrent liabilities		Other noncurrent liabilities
Long-term finance lease liabilities	$ 32,189		$ 14,357
Total finance lease liabilities	$ 36,887		$ 18,377
Weighted average remaining lease term (years):
Operating leases	7 years 8 months 12 days		8 years 4 months 24 days
Finance lease	10 years 7 months 6 days		6 years
Weighted average discount rate:
Operating leases	7.10%		5.10%
Finance leases	8.10%		7.70%
Operating Leases
2024 (nine months)	$ 17,288
2025	20,808
2026	17,554
2027	14,089
2028	10,906
2029	9,407
Thereafter	33,031
Total lease payments	123,083
Less imputed interest	(27,720)
Present value of lease payments	95,363		$ 41,826
Finance Leases
2024 (nine months)	5,734
2025	6,570
2026	5,072
2027	4,870
2028	4,627
2029	4,477
Thereafter	24,743
Total lease payments	56,093
Less imputed interest	(19,206)
Present value of lease payments	$ 36,887		$ 18,377