Property, Plant and Equipment, net and Intangibles, net - Components of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,247,265	$ 1,931,006
Less accumulated depreciation, depletion and amortization	(631,841)	(484,554)
Property, plant and equipment, net	1,615,424	1,446,452
Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,247,265	1,931,006
Less accumulated depreciation, depletion and amortization	(631,841)	(484,554)
Property, plant and equipment, net	1,615,424	1,446,452
Land (mineral bearing) and asset retirement costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	274,083	227,558
Land (mineral bearing) and asset retirement costs | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	274,083	227,558
Land (non-mineral bearing)
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	168,501	146,099
Land (non-mineral bearing) | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	168,501	146,099
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 170,615	160,638
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Buildings and improvements | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 170,615	160,638
Buildings and improvements | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Buildings and improvements | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Plants, machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,068,007	965,522
Plants, machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Plants, machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Plants, machinery and equipment | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,068,007	965,522
Plants, machinery and equipment | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Plants, machinery and equipment | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Mobile equipment and barges
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 391,256	307,885
Mobile equipment and barges | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Mobile equipment and barges | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Mobile equipment and barges | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 391,256	307,885
Mobile equipment and barges | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Mobile equipment and barges | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 33,314	26,096
Office equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Office equipment | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 33,314	26,096
Office equipment | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Truck and auto fleet
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 47,270	32,236
Truck and auto fleet | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Truck and auto fleet | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Truck and auto fleet | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 47,270	32,236
Truck and auto fleet | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Truck and auto fleet | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Landfill airspace and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 49,480	48,513
Landfill airspace and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Landfill airspace and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Landfill airspace and improvements | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 49,480	48,513
Landfill airspace and improvements | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Landfill airspace and improvements | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 44,739	16,459
Construction in progress | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 44,739	$ 16,459
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Other | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Other | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years