Income Taxes - Components of Income Tax Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Provision for income taxes:
Current	$ 69	$ 463	$ 2,530
Deferred	17,032	59,284	(286,507)
Income tax expense (benefit)	17,101	59,747	(283,977)
Summit Materials, LLC
Provision for income taxes:
Current	69	463	2,762
Deferred	6,316	9,810	(23,107)
Income tax expense (benefit)	$ 6,385	$ 10,273	$ (20,345)