GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Schedule of Condensed Consolidating Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2022	Apr. 03, 2021
Condensed Consolidating Statements of Operations
Revenue	$ 420,947	$ 427,844
Cost of revenue (excluding items shown separately below)	353,380	346,694
Depreciation, depletion, amortization and accretion	51,193	56,336
Operating (loss) income	(34,295)	(25,059)
Other income, net	(696)	(4,889)
Gain on sale of businesses	(14,205)	(15,668)
Loss from operations before taxes	(39,543)	(28,688)
Income tax benefit	(4,743)	(5,443)
Net income (loss) attributable to Summit Inc/LLC	(34,292)	(22,517)
Comprehensive (loss) income attributable to member of Summit Materials, LLC	(32,986)	(20,882)
Summit Materials, LLC
Condensed Consolidating Statements of Operations
Revenue	420,947	427,844
Cost of revenue (excluding items shown separately below)	353,380	346,694
General and administrative expenses	50,669	49,873
Depreciation, depletion, amortization and accretion	51,193	56,336
Operating (loss) income	(34,295)	(25,059)
Other income, net	(696)	(4,889)
Interest expense (income)	20,149	24,124
Gain on sale of businesses	(14,205)	(15,668)
Loss from operations before taxes	(39,543)	(28,626)
Income tax benefit	6,844	(836)
Net income (loss) attributable to Summit Inc/LLC	(46,387)	(27,790)
Comprehensive (loss) income attributable to member of Summit Materials, LLC	(44,643)	(25,664)
Summit Materials, LLC | Eliminations
Condensed Consolidating Statements of Operations
Revenue	(1,330)	(2,268)
Cost of revenue (excluding items shown separately below)	(1,330)	(2,268)
General and administrative expenses	0	0
Depreciation, depletion, amortization and accretion	0	0
Operating (loss) income	0	0
Other income, net	5,782	25,489
Interest expense (income)	0	0
Gain on sale of businesses	0
Loss from operations before taxes	(5,782)	(25,489)
Income tax benefit	0	0
Net income (loss) attributable to Summit Inc/LLC	(5,782)	(25,489)
Comprehensive (loss) income attributable to member of Summit Materials, LLC	(4,038)	(23,363)
Issuers | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	0	0
Cost of revenue (excluding items shown separately below)	0	0
General and administrative expenses	17,304	18,591
Depreciation, depletion, amortization and accretion	750	1,104
Operating (loss) income	(18,054)	(19,695)
Other income, net	(5,919)	(25,560)
Interest expense (income)	33,902	33,291
Gain on sale of businesses	0
Loss from operations before taxes	(46,037)	(27,426)
Income tax benefit	350	364
Net income (loss) attributable to Summit Inc/LLC	(46,387)	(27,790)
Comprehensive (loss) income attributable to member of Summit Materials, LLC	(44,643)	(25,664)
Guarantors  | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	395,180	407,301
Cost of revenue (excluding items shown separately below)	334,264	331,844
General and administrative expenses	31,672	29,849
Depreciation, depletion, amortization and accretion	47,496	52,566
Operating (loss) income	(18,252)	(6,958)
Other income, net	(552)	(4,337)
Interest expense (income)	(15,123)	(10,543)
Gain on sale of businesses	(14,205)
Loss from operations before taxes	11,628	23,590
Income tax benefit	6,318	(1,385)
Net income (loss) attributable to Summit Inc/LLC	5,310	24,975
Comprehensive (loss) income attributable to member of Summit Materials, LLC	5,310	24,975
Non-Guarantors | Summit Materials, LLC | Reportable Legal Entities
Condensed Consolidating Statements of Operations
Revenue	27,097	22,811
Cost of revenue (excluding items shown separately below)	20,446	17,118
General and administrative expenses	1,693	1,433
Depreciation, depletion, amortization and accretion	2,947	2,666
Operating (loss) income	2,011	1,594
Other income, net	(7)	(481)
Interest expense (income)	1,370	1,376
Gain on sale of businesses	0
Loss from operations before taxes	648	699
Income tax benefit	176	185
Net income (loss) attributable to Summit Inc/LLC	472	514
Comprehensive (loss) income attributable to member of Summit Materials, LLC	$ (1,272)	$ (1,612)