GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Schedule of Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2022	Apr. 03, 2021
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	$ (16,713)	$ (21,318)
Cash flows from investing activities:
Purchase of property, plant and equipment	(57,774)	(69,757)
Proceeds from the sale of property, plant, and equipment	1,439	2,663
Proceeds from sale of businesses	47,821	33,077
Other	(857)	(483)
Net cash used in investing activities	(9,371)	(34,500)
Cash flows from financing activities:
Payments on long-term debt	(7,603)	(10,170)
Payments on acquisition-related liabilities	(11,397)	(8,096)
Other	(1,180)	(416)
Net cash used in financing activities	(67,662)	(2,762)
Impact of foreign currency on cash	177	140
Net decrease in cash	(93,569)	(58,440)
Cash and cash equivalents—beginning of period	380,961	418,181
Cash and cash equivalents—end of period	287,392	359,741
Summit Materials, LLC
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	(16,713)	(21,318)
Cash flows from investing activities:
Purchase of property, plant and equipment	(57,774)	(69,757)
Proceeds from the sale of property, plant, and equipment	1,439	2,663
Proceeds from sale of businesses	47,821	33,077
Other	(857)	(483)
Net cash used in investing activities	(9,371)	(34,500)
Cash flows from financing activities:
Proceeds from investment by member	(47,482)	15,920
Loans received from and payments made on loans from other Summit Companies	0	0
Payments on long-term debt	(7,603)	(10,170)
Payments on acquisition-related liabilities	(11,397)	(5,596)
Distributions from partnership	0	(2,500)
Other	(1,180)	(416)
Net cash used in financing activities	(67,662)	(2,762)
Impact of foreign currency on cash	177	140
Net decrease in cash	(93,569)	(58,440)
Cash and cash equivalents—beginning of period	380,961	418,181
Cash and cash equivalents—end of period	287,392	359,741
Summit Materials, LLC | Eliminations
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	0	0
Cash flows from investing activities:
Purchase of property, plant and equipment	0	0
Proceeds from the sale of property, plant, and equipment	0	0
Proceeds from sale of businesses	0	0
Other	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities:
Proceeds from investment by member	0	0
Loans received from and payments made on loans from other Summit Companies	702	1,023
Payments on long-term debt	0	0
Payments on acquisition-related liabilities	0	0
Distributions from partnership		0
Other	0	0
Net cash used in financing activities	702	1,023
Impact of foreign currency on cash	0	0
Net decrease in cash	702	1,023
Cash and cash equivalents—beginning of period	(4,684)	(3,641)
Cash and cash equivalents—end of period	(3,982)	(2,618)
Summit Materials, LLC | Issuers | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	(48,551)	(44,988)
Cash flows from investing activities:
Purchase of property, plant and equipment	(459)	(215)
Proceeds from the sale of property, plant, and equipment	0	0
Proceeds from sale of businesses	0	0
Other	0	0
Net cash used in investing activities	(459)	(215)
Cash flows from financing activities:
Proceeds from investment by member	(47,482)	15,920
Loans received from and payments made on loans from other Summit Companies	4,703	(21,350)
Payments on long-term debt	(1,588)	(1,589)
Payments on acquisition-related liabilities	0	0
Distributions from partnership		(2,500)
Other	(1,180)	(416)
Net cash used in financing activities	(45,547)	(9,935)
Impact of foreign currency on cash	0	0
Net decrease in cash	(94,557)	(55,138)
Cash and cash equivalents—beginning of period	365,044	401,074
Cash and cash equivalents—end of period	270,487	345,936
Summit Materials, LLC | Guarantors  | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	25,873	18,590
Cash flows from investing activities:
Purchase of property, plant and equipment	(55,522)	(67,795)
Proceeds from the sale of property, plant, and equipment	1,360	2,457
Proceeds from sale of businesses	47,821	33,077
Other	(857)	(483)
Net cash used in investing activities	(7,198)	(32,744)
Cash flows from financing activities:
Proceeds from investment by member	0	0
Loans received from and payments made on loans from other Summit Companies	(2,052)	22,390
Payments on long-term debt	(6,015)	(8,531)
Payments on acquisition-related liabilities	(11,397)	(5,596)
Distributions from partnership		0
Other	0	0
Net cash used in financing activities	(19,464)	8,263
Impact of foreign currency on cash	0	0
Net decrease in cash	(789)	(5,891)
Cash and cash equivalents—beginning of period	2,264	10,287
Cash and cash equivalents—end of period	1,475	4,396
Summit Materials, LLC | Non-Guarantors | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	5,965	5,080
Cash flows from investing activities:
Purchase of property, plant and equipment	(1,793)	(1,747)
Proceeds from the sale of property, plant, and equipment	79	206
Proceeds from sale of businesses	0	0
Other	0	0
Net cash used in investing activities	(1,714)	(1,541)
Cash flows from financing activities:
Proceeds from investment by member	0	0
Loans received from and payments made on loans from other Summit Companies	(3,353)	(2,063)
Payments on long-term debt	0	(50)
Payments on acquisition-related liabilities	0	0
Distributions from partnership		0
Other	0	0
Net cash used in financing activities	(3,353)	(2,113)
Impact of foreign currency on cash	177	140
Net decrease in cash	1,075	1,566
Cash and cash equivalents—beginning of period	18,337	10,461
Cash and cash equivalents—end of period	$ 19,412	$ 12,027