Income Taxes - Deferred Tax Assets and Tax Receivable Agreement (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Mar. 11, 2015	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Income Taxes
Income tax expense (benefit)		$ (483,584)	$ 1,309	$ (482,327)	$ (7,913)
Deferred tax liabilities		29,600		488,852
Tax receivable agreement payable		548,885		548,885		$ 58,145
Tax receivable agreement expense		489,215		$ 490,740
Number of Summit LP units purchased by Company, newly issued units (in shares)				1,255,266
Deferred tax asset, Investment in limited partnership		14,700		$ 14,700
Tax distribution paid				100
Valuation Allowance
Valuation allowance		(2,677)		(2,677)		(502,839)
Accrued expenses.
Income Taxes
Tax receivable agreement payable						$ 1,100
Tax Receivable Agreement
Income Taxes
Percentage of benefits to be paid on tax receivable agreement	85.00%
Summit Materials, LLC
Income Taxes
Income tax expense (benefit)		$ 5,286	$ 1,309	$ 6,543	(7,896)
Summit Holdings LP
Income Taxes
Tax distribution paid					25,500
Distributions to LP Unitholders					9,000
Distributions to Summit Inc.					$ 16,500
Summit Holdings LP | Tax Receivable Agreement
Income Taxes
Percentage of benefits to be paid on tax receivable agreement				85.00%