ACQUISITIONS, DISPOSTIONS, GOODWILL AND INTANGIBLES - Schedule of Business Combination Recognizable Assets and Liabilities Assumed (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 02, 2021	Jan. 02, 2021
Business Acquisition [Line Items]
Goodwill	$ 1,174,855	$ 1,201,291
Summit Materials, LLC
Business Acquisition [Line Items]
Goodwill	1,175,855	1,202,291
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Financial assets	0	8,696
Inventories	173	2,856
Property, plant and equipment	7,958	130,042
Intangible assets	702	0
Other assets	0	2,790
Financial liabilities	(121)	(4,469)
Other long-term liabilities	(300)	(16,069)
Net assets acquired	8,412	123,846
Goodwill	0	0
Purchase price	8,412	123,846
Acquisition-related liabilities	(1,149)	0
Other	0	(369)
Net cash paid for acquisitions	7,263	123,477
Series of Individually Immaterial Business Acquisitions | Summit Materials, LLC
Business Acquisition [Line Items]
Financial assets	0	8,696
Inventories	173	2,856
Property, plant and equipment	7,958	130,042
Intangible assets	702	0
Other assets	0	2,790
Financial liabilities	(121)	(4,469)
Other long-term liabilities	(300)	(16,069)
Net assets acquired	8,412	123,846
Goodwill	0	0
Purchase price	8,412	123,846
Acquisition-related liabilities	(1,149)	0
Other	0	(369)
Net cash paid for acquisitions	$ 7,263	$ 123,477