Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Each Component of Accumulated Comprehensive Income Loss (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Jan. 02, 2016	Dec. 27, 2014
Changes in each component of accumulated other comprehensive loss
Beginning balance	$ 628,265
Postretirement curtailment adjustment			$ (1,346)
Ending balance	842,044	$ 628,265
Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	(2,795)
Postretirement liability adjustment	(401)	(1,049)
Foreign currency translation adjustment	273	(3,379)
Loss on cash flow hedges	(128)	(465)
Ending balance	(2,249)	(2,795)
Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	1,049
Postretirement liability adjustment	(401)	(1,049)
Ending balance	1,450	1,049
Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	(3,379)
Foreign currency translation adjustment	273	(3,379)
Ending balance	(3,106)	(3,379)
Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	(465)
Loss on cash flow hedges	(128)	(465)
Ending balance	(593)	(465)
Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Postretirement curtailment adjustment			(1,346)
Summit Materials, LLC \| Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	(28,466)	(15,546)	(6,045)
Postretirement curtailment adjustment			(942)
Postretirement liability adjustment	426	2,123	(2,743)
Foreign currency translation adjustment	2,125	(14,099)	(5,816)
Loss on cash flow hedges	(1,529)	(944)
Ending balance	(27,444)	(28,466)	(15,546)
Summit Materials, LLC \| Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	(7,607)	(9,730)	(6,045)
Postretirement curtailment adjustment			(942)
Postretirement liability adjustment	426	2,123	(2,743)
Ending balance	(7,181)	(7,607)	(9,730)
Summit Materials, LLC \| Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	(19,915)	(5,816)
Foreign currency translation adjustment	2,125	(14,099)	(5,816)
Ending balance	(17,790)	(19,915)	$ (5,816)
Summit Materials, LLC \| Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	(944)
Loss on cash flow hedges	(1,529)	(944)
Ending balance	$ (2,473)	$ (944)

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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- Definition

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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- Definition

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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Amount after tax of gain (loss) adjustment to other comprehensive income (loss) resulting from settlement or curtailment of defined benefit pension and other postretirement defined benefit plans.

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- Definition

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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