Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Each Component of Accumulated Comprehensive Income Loss (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2017	Oct. 01, 2016
Changes in each component of accumulated other comprehensive loss
Beginning balance	$ 842,044
Ending balance	1,201,560
Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	(2,249)	$ (2,795)
Postretirement liability adjustment	397
Foreign currency translation adjustment	8,172	1,661
Income (loss) on cash flow hedges	368	(1,731)
Ending balance	6,688	(2,865)
Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	1,450	1,049
Postretirement liability adjustment	397
Ending balance	1,847	1,049
Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	(3,106)	(3,379)
Foreign currency translation adjustment	8,172	1,661
Ending balance	5,066	(1,718)
Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	(593)	(465)
Income (loss) on cash flow hedges	368	(1,731)
Ending balance	(225)	(2,196)
Summit Materials, LLC \| Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	(27,444)	(28,466)
Postretirement liability adjustment	413
Foreign currency translation adjustment	8,498	3,966
Income (loss) on cash flow hedges	384	(3,232)
Ending balance	(18,149)	(27,732)
Summit Materials, LLC \| Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	(7,181)	(7,607)
Postretirement liability adjustment	413
Ending balance	(6,768)	(7,607)
Summit Materials, LLC \| Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	(17,790)	(19,915)
Foreign currency translation adjustment	8,498	3,966
Ending balance	(9,292)	(15,949)
Summit Materials, LLC \| Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	(2,473)	(944)
Income (loss) on cash flow hedges	384	(3,232)
Ending balance	$ (2,089)	$ (4,176)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans, attributable to parent entity.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss), attributable to parent entity.

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- Definition

Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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