FAIR VALUE - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 30, 2024	Dec. 30, 2023
Financial Instruments
Current portion of long-term debt	$ 7,575	$ 3,822
Summit Materials, LLC
Financial Instruments
Current portion of long-term debt	7,575	3,822
Level 1 | Fair Value
Financial Instruments
Long-term debt	2,826,313	2,329,606
Level 1 | Carrying Value
Financial Instruments
Long-term debt	2,807,601	2,300,473
Level 1 | Summit Materials, LLC
Financial Instruments
Current portion of long-term debt	7,600	3,800
Level 1 | Summit Materials, LLC | Fair Value
Financial Instruments
Long-term debt	2,826,313	2,329,606
Level 1 | Summit Materials, LLC | Carrying Value
Financial Instruments
Long-term debt	2,807,601	2,300,473
Level 3 | Fair Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	7,292	6,868
Long term portion of deferred consideration and noncompete obligations	12,928	18,767
Level 3 | Carrying Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	7,292	6,868
Long term portion of deferred consideration and noncompete obligations	12,928	18,767
Level 3 | Summit Materials, LLC | Fair Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	7,292	6,868
Long term portion of deferred consideration and noncompete obligations	12,928	18,767
Level 3 | Summit Materials, LLC | Carrying Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	7,292	6,868
Long term portion of deferred consideration and noncompete obligations	12,928	18,767
Fair Value, Inputs, Level 1 | Fair Value
Financial Instruments
Current portion of long-term debt	$ 7,600	$ 3,800