Acquisitions - Summary of Assets Acquired and Liabilities Assumed (Detail) $ in Thousands			3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 10, 2017 USD ($)	Aug. 30, 2016 facility	Apr. 01, 2017 USD ($)	Jul. 01, 2017 USD ($) facility	Jul. 02, 2016 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Net gain on asset disposals				$ 4,052	$ 3,717
Goodwill				$ 918,511		$ 782,212
Cement plant
Business Acquisition [Line Items]
Number of Plants Owned and Operated | facility				2
Follow on Public Offering
Business Acquisition [Line Items]
Cash paid for acquisitions	$ 110,000
Cement
Business Acquisition [Line Items]
Goodwill				$ 204,656		204,538
Summit Materials, LLC
Business Acquisition [Line Items]
Net gain on asset disposals				4,052	$ 3,717
Goodwill				918,511		782,212
Summit Materials, LLC | Cement
Business Acquisition [Line Items]
Goodwill				204,656		204,538
2016 Acquisitions
Business Acquisition [Line Items]
Financial assets						22,204
Inventories						17,215
Property, plant and equipment						180,321
Intangible assets						5,531
Other assets						6,757
Financial liabilities						(20,248)
Other long-term liabilities						(36,074)
Net assets acquired						175,706
Goodwill						176,319
Purchase price						352,025
Acquisition related liabilities						(17,034)
Other						1,967
Net cash paid for acquisitions						336,958
Amount reclassified from financial assets to liabilities			$ 1,200
2016 Acquisitions | Summit Materials, LLC
Business Acquisition [Line Items]
Financial assets						22,204
Inventories						17,215
Property, plant and equipment						180,321
Intangible assets						5,531
Other assets						6,757
Financial liabilities						(20,248)
Other long-term liabilities						(36,074)
Net assets acquired						175,706
Goodwill						176,319
Purchase price						352,025
Acquisition related liabilities						(17,034)
Other						1,967
Net cash paid for acquisitions						$ 336,958
Amount reclassified from financial assets to liabilities			$ 1,200
2017 Acquisitions
Business Acquisition [Line Items]
Financial assets				18,042
Inventories				6,099
Property, plant and equipment				84,402
Intangible assets				13
Other assets				3,477
Financial liabilities				(10,751)
Other long-term liabilities				(4,157)
Net assets acquired				97,125
Goodwill				130,582
Purchase price				227,707
Acquisition related liabilities				(13,390)
Other				(1,193)
Net cash paid for acquisitions				213,124
2017 Acquisitions | Summit Materials, LLC
Business Acquisition [Line Items]
Financial assets				18,042
Inventories				6,099
Property, plant and equipment				84,402
Intangible assets				13
Other assets				3,477
Financial liabilities				(10,751)
Other long-term liabilities				(4,157)
Net assets acquired				97,125
Goodwill				130,582
Purchase price				227,707
Acquisition related liabilities				(13,390)
Other				(1,193)
Net cash paid for acquisitions				$ 213,124
Angelle Assets | Cement | Cement terminal
Business Acquisition [Line Items]
Number of plants acquired | facility		2