Fair Value - Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 30, 2017	Dec. 31, 2016
Level 3
Fair Value Measurements
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	$ 594	$ 9,288
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	$ 34,301	2,377
Discount rate	11.00%
Adjustment to contingent consideration		6,100
Cash flow hedges \| Interest rate derivatives \| Level 2
Fair Value Measurements
Current portion of acquisition-related liabilities and Accrued expenses - Cash flow hedge	$ 488	942
Acquisition-related liabilities and Other noncurrent liabilities - Cash flow hedge	492	1,438
Cash flow hedges \| Interest rate derivatives \| Term Loan, due 2022
Fair Value Measurements
Term loan borrowings hedged by derivatives	200,000	200,000
Summit Materials, LLC \| Level 3
Fair Value Measurements
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	594	9,288
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	$ 34,301	2,377
Discount rate	11.00%
Adjustment to contingent consideration		6,100
Summit Materials, LLC \| Cash flow hedges \| Interest rate derivatives \| Level 2
Fair Value Measurements
Current portion of acquisition-related liabilities and Accrued expenses - Cash flow hedge	$ 488	942
Acquisition-related liabilities and Other noncurrent liabilities - Cash flow hedge	492	1,438
Summit Materials, LLC \| Cash flow hedges \| Interest rate derivatives \| Term Loan, due 2022
Fair Value Measurements
Term loan borrowings hedged by derivatives	$ 200,000	$ 200,000

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

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Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

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Amount of the hedged item as of the balance sheet date related to the derivative. For example, the hedged balance on a debt instrument.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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