Revenue Recognition - By Product (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Revenue from External Customer [Line Items]
Total revenue	$ 694,661	$ 634,181	$ 1,609,972	$ 1,442,551
Aggregates
Revenue from External Customer [Line Items]
Total revenue	109,621	90,594	280,761	236,437
Cement
Revenue from External Customer [Line Items]
Total revenue	87,909	94,915	197,439	213,243
Ready-mix concrete
Revenue from External Customer [Line Items]
Total revenue	164,866	139,934	447,490	361,824
Asphalt
Revenue from External Customer [Line Items]
Total revenue	125,153	115,917	231,666	218,934
Paving and related services
Revenue from External Customer [Line Items]
Total revenue	146,477	136,445	288,119	270,449
Other
Revenue from External Customer [Line Items]
Total revenue	60,635	56,376	164,497	141,664
Summit Materials, LLC
Revenue from External Customer [Line Items]
Total revenue	694,661	634,181	1,609,972	1,442,551
Summit Materials, LLC | Aggregates
Revenue from External Customer [Line Items]
Total revenue	109,621	90,594	280,761	236,437
Summit Materials, LLC | Cement
Revenue from External Customer [Line Items]
Total revenue	87,909	94,915	197,439	213,243
Summit Materials, LLC | Ready-mix concrete
Revenue from External Customer [Line Items]
Total revenue	164,866	139,934	447,490	361,824
Summit Materials, LLC | Asphalt
Revenue from External Customer [Line Items]
Total revenue	125,153	115,917	231,666	218,934
Summit Materials, LLC | Paving and related services
Revenue from External Customer [Line Items]
Total revenue	146,477	136,445	288,119	270,449
Summit Materials, LLC | Other
Revenue from External Customer [Line Items]
Total revenue	$ 60,635	$ 56,376	$ 164,497	$ 141,664