Acquisitions - Completed Acquisitions Information (Detail)	Sep. 06, 2017 item	Aug. 03, 2017 item	Aug. 01, 2017 facility item	Jul. 31, 2017 facility	Jul. 28, 2017 facility	Apr. 03, 2017 item	Mar. 17, 2017 facility	Jan. 30, 2017 facility	Oct. 03, 2016 facility	Aug. 30, 2016 facility item	Aug. 19, 2016 facility	May 20, 2016 item	Apr. 29, 2016 facility item	Mar. 18, 2016 facility item	Feb. 05, 2016 item	Sep. 30, 2017	Dec. 31, 2016
8 1/2% Senior Notes, due 2022
Business Acquisition [Line Items]
Debt Instrument, Interest Rate, Stated Percentage																8.50%	8.50%
Cement | Cement terminal
Business Acquisition [Line Items]
Number of plants acquired										2
Summit Materials, LLC | 8 1/2% Senior Notes, due 2022
Business Acquisition [Line Items]
Debt Instrument, Interest Rate, Stated Percentage																8.50%	8.50%
Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired											12
Summit Materials, LLC | Cement | Cement terminal
Business Acquisition [Line Items]
Number of plants acquired | item										2
Northwest Ready Mix, Inc | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item			1
Northwest Ready Mix, Inc | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired			3
Northwest Ready Mix, Inc | Summit Materials, LLC | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item			1
Northwest Ready Mix, Inc | Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired			3
Great Southern | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired				2
Great Southern | Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired				2
Columbia Silica | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item	4
Columbia Silica | Summit Materials, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item	4
Georgia Stone | East | Aggregates
Business Acquisition [Line Items]
Number of quarries | item		2
Georgia Stone | Summit Materials, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of quarries | item		2
Somerset | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired					10
Somerset | Summit Materials, LLC | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired					10
Hanna's Bend Aggregate, Ltd | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item						1
Hanna's Bend Aggregate, Ltd | Summit Materials, LLC | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item						1
Everist Materials, LLC | West | Aggregates | Cement plant
Business Acquisition [Line Items]
Number of plants acquired								2
Everist Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired								5
Everist Materials, LLC | West | Asphalt
Business Acquisition [Line Items]
Number of plants acquired								2
Everist Materials, LLC | Summit Materials, LLC | West | Aggregates | Cement plant
Business Acquisition [Line Items]
Number of plants acquired								2
Everist Materials, LLC | Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired								5
Everist Materials, LLC | Summit Materials, LLC | West | Asphalt
Business Acquisition [Line Items]
Number of plants acquired								2
Carolina Sand, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item						4
Carolina Sand, LLC | Summit Materials, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item						4
Midland Concrete | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired									1
Midland Concrete | Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired									1
Sandidge Concrete | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired							3
Sandidge Concrete | Summit Materials, LLC | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired							3
Rustin | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired											12
Sierra Ready Mix, LLC | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item													1
Sierra Ready Mix, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired													2
Sierra Ready Mix, LLC | Summit Materials, LLC | West | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item													1
Sierra Ready Mix, LLC | Summit Materials, LLC | West | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired | item													2
APAC Kansas Inc | East | Aggregates
Business Acquisition [Line Items]
Number of quarries | item												7
APAC Kansas Inc | Summit Materials, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of quarries | item												7
Boxley | East | Aggregates
Business Acquisition [Line Items]
Number of quarries | item														6
Boxley | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired														4
Boxley | East | Asphalt
Business Acquisition [Line Items]
Number of plants acquired														4
Boxley | Summit Materials, LLC | East | Ready-mixed concrete | Cement plant
Business Acquisition [Line Items]
Number of plants acquired														4
Boxley | Summit Materials, LLC | East | Asphalt
Business Acquisition [Line Items]
Number of plants acquired														4
AMC | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item															5
AMC | Summit Materials, LLC | East | Aggregates
Business Acquisition [Line Items]
Number of sand and gravel pits acquired | item															5