Segment Information - By Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Revenue by product
Total revenue	$ 1,932,575	$ 1,626,063	$ 1,432,297
Aggregates
Revenue by product
Total revenue	313,383	264,609	219,040
Cement
Revenue by product
Total revenue	282,041	250,349	167,696
Ready-mixed concrete
Revenue by product
Total revenue	492,302	395,917	350,262
Asphalt
Revenue by product
Total revenue	285,653	239,419	252,031
Paving and related services
Revenue by product
Total revenue	371,763	304,041	295,995
Other
Revenue by product
Total revenue	187,433	171,728	147,273
Summit Materials, LLC
Revenue by product
Total revenue	1,932,575	1,626,063	1,432,297
Summit Materials, LLC | Aggregates
Revenue by product
Total revenue	313,383	264,609	219,040
Summit Materials, LLC | Cement
Revenue by product
Total revenue	282,041	250,349	167,696
Summit Materials, LLC | Ready-mixed concrete
Revenue by product
Total revenue	492,302	395,917	350,262
Summit Materials, LLC | Asphalt
Revenue by product
Total revenue	285,653	239,419	252,031
Summit Materials, LLC | Paving and related services
Revenue by product
Total revenue	371,763	304,041	295,995
Summit Materials, LLC | Other
Revenue by product
Total revenue	$ 187,433	$ 171,728	$ 147,273