Income Taxes - Schedule of Income Tax Benefit (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Line Items]
Income tax benefit (expense) at federal statutory tax rate	$ (55,365)	$ 14,290	$ (6,718)
Less: Income tax (benefit) expense at federal statutory tax rate for LLC entities	(2,123)	(10,608)	(22,649)
State and local income taxes	(5,209)	2,490	(2,389)
Permanent differences	(4,410)	(5,902)	2,147
Effective tax rate change	216,904	(1,432)	10
Tax receivable agreement expense	104,804	5,228
Change in valuation allowance	(500,162)	239,008	261,302
Impact of LP Unit ownership change	(31,790)	(252,456)	(249,400)
Other	(6,626)	4,083	(566)
Income tax expense (benefit)	$ (283,977)	(5,299)	(18,263)
U.S. statutory rate	35.00%
Summit Materials, LLC
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Line Items]
Income tax benefit (expense) at federal statutory tax rate	$ 39,797	19,882	(6,412)
Less: Income tax (benefit) expense at federal statutory tax rate for LLC entities	(36,171)	(21,042)	(9,908)
State and local income taxes	1,751	1,279	(2,389)
Permanent differences	(630)	(1,726)	2,147
Effective tax rate change	(24,243)	(1,432)	10
Change in valuation allowance		148
Other	(849)	(2,408)	(1,711)
Income tax expense (benefit)	$ (20,345)	$ (5,282)	$ (18,263)
U.S. statutory rate	35.00%