SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands		3 Months Ended
	Jan. 12, 2024 USD ($) shares	Mar. 30, 2024 USD ($) state cementPlant segment	Apr. 01, 2023 USD ($)	Dec. 30, 2023 USD ($)
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments | segment		3
Number of reportable segments | segment		3
Proceeds from debt issuances		$ 1,007,475	$ 0
Number of states in which the entity operates | state		24
Transaction and integration costs		$ 62,208	364
Deferred tax liabilities		$ 205,669		$ 15,854
Argos USA
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Cash consideration	$ 1,200,000
Net cash paid for acquisitions	3,119,213
Argos USA | Seven Point Two Five Percent Senior Notes Due Two Thousand Thirty One | Senior Notes
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Proceeds from debt issuances	$ 800,000
Argos USA | Preferred Stock
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Business acquisition number of shares (in shares) | shares	1
Argos USA | Common Class A
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Business acquisition number of shares (in shares) | shares	54,720,000
Revision of Prior Period, Reclassification, Adjustment
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Transaction and integration costs			400
Deferred tax liabilities				15,900
Cement plant
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of plants | cementPlant		6
Summit Materials, LLC
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments | segment		3
Number of reportable segments | segment		3
Proceeds from debt issuances		$ 1,007,475	0
Number of states in which the entity operates | state		24
Transaction and integration costs		$ 62,208	$ 364
Deferred tax liabilities		$ 342,040		$ 100,812
Summit Materials, LLC | Argos USA
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Cash consideration	$ 1,200,000
Net cash paid for acquisitions	3,119,213
Summit Materials, LLC | Argos USA | Seven Point Two Five Percent Senior Notes Due Two Thousand Thirty One | Senior Notes
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Proceeds from debt issuances	$ 800,000
Summit Materials, LLC | Argos USA | Preferred Stock
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Business acquisition number of shares (in shares) | shares	1
Summit Materials, LLC | Argos USA | Common Class A
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Business acquisition number of shares (in shares) | shares	54,720,000
Summit Materials, LLC | Cement plant
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of plants | cementPlant		6