Summit Materials (SUM) 10-Q 3 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	Sep. 26, 2015	Sep. 26, 2015	Oct. 27, 2015
Document Information [Line Items]
Document Type		10-Q
Amendment Flag		false
Document Period End Date		Sep. 26, 2015
Document Fiscal Year Focus		2,015
Document Fiscal Period Focus		Q3
Trading Symbol		SUM
Entity Registrant Name		SUMMIT MATERIALS, INC.
Entity Central Index Key		1,621,563
Current Fiscal Year End Date		--12-26
Entity Filer Category		Non-accelerated Filer
Membership interests description	As of October 27, 2015, 100% of Summit Materials, LLC’s outstanding limited liability company interests were held by Summit Materials Intermediate Holdings, LLC, its sole member and an indirect subsidiary of Summit Materials, Inc.
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding			49,009,738
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding			69,007,297
Summit Materials, LLC [Member]
Document Information [Line Items]
Document Type		10-Q
Amendment Flag		false
Document Period End Date		Sep. 26, 2015
Document Fiscal Year Focus		2,015
Document Fiscal Period Focus		Q3
Entity Registrant Name		SUMMIT MATERIALS, LLC
Entity Central Index Key		1,571,371
Current Fiscal Year End Date		--12-26
Entity Filer Category		Non-accelerated Filer
Membership interests percentage			100.00%

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 18,987	$ 13,215
Accounts receivable, net	205,939	141,302
Costs and estimated earnings in excess of billings	34,175	10,174
Inventories	138,036	111,553
Other current assets	21,762	17,172
Total current assets	418,899	293,416
Property, plant and equipment, less accumulated depreciation, depletion and amortization (September 26, 2015 - $343,087 and December 27, 2014 - $279,375)	1,276,227	950,601
Goodwill	567,836	419,270
Intangible assets, less accumulated amortization (September 26, 2015 - $4,851 and December 27, 2014 - $3,073)	15,481	17,647
Other assets	51,798	48,843
Total assets	2,330,241	1,729,777
Current liabilities:
Current portion of debt	68,125	5,275
Current portion of acquisition-related liabilities	20,191	18,402
Accounts payable	113,226	78,854
Accrued expenses	90,880	101,496
Billings in excess of costs and estimated earnings	11,005	8,958
Total current liabilities	303,427	212,985
Long-term debt	1,148,068	1,059,642
Acquisition-related liabilities	41,978	42,736
Other noncurrent liabilities	114,575	93,691
Total liabilities	$ 1,608,048	$ 1,409,054
Commitments and contingencies
Redeemable noncontrolling interest		$ 33,740
Stockholders' Equity/Partners' Interest:
Accumulated earnings/deficit	$ 4,355
Accumulated other comprehensive loss	(2,607)
Partners' interest		285,685
Additional paid-in capital	600,204
Stockholders' equity/partners' interest:	603,132	285,685
Total liabilities, redeemable noncontrolling interest and member's interest	2,330,241	1,729,777
Total stockholders' equity/partners' interest	722,193	286,983
Common Class A [Member]
Stockholders' Equity/Partners' Interest:
Common stock	490
Total stockholders' equity/partners' interest	490
Common Class B [Member]
Stockholders' Equity/Partners' Interest:
Common stock	690
Total stockholders' equity/partners' interest	690
Summit Materials, LLC [Member]
Current assets:
Cash and cash equivalents	5,482	13,215
Accounts receivable, net	205,939	141,302
Costs and estimated earnings in excess of billings	34,175	10,174
Inventories	138,036	111,553
Other current assets	21,762	17,172
Total current assets	405,394	293,416
Property, plant and equipment, less accumulated depreciation, depletion and amortization (September 26, 2015 - $343,087 and December 27, 2014 - $279,375)	1,276,227	950,601
Goodwill	567,836	419,270
Intangible assets, less accumulated amortization (September 26, 2015 - $4,851 and December 27, 2014 - $3,073)	15,481	17,647
Other assets	51,798	48,843
Total assets	2,316,736	1,729,777
Current liabilities:
Current portion of debt	68,125	5,275
Current portion of acquisition-related liabilities	17,691	18,402
Accounts payable	113,226	78,854
Accrued expenses	90,880	101,496
Billings in excess of costs and estimated earnings	11,005	8,958
Total current liabilities	300,927	212,985
Long-term debt	1,148,068	1,059,642
Acquisition-related liabilities	33,320	42,736
Other noncurrent liabilities	114,575	93,691
Total liabilities	$ 1,596,890	$ 1,409,054
Commitments and contingencies
Redeemable noncontrolling interest		$ 33,740
Member's equity	$ 1,039,763	518,647
Stockholders' Equity/Partners' Interest:
Accumulated earnings/deficit	(293,101)	(217,416)
Accumulated other comprehensive loss	(28,087)	(15,546)
Member's interest	718,575	285,685
Noncontrolling interest	1,271	1,298
Total member's interest	719,846	286,983
Total liabilities, redeemable noncontrolling interest and member's interest	2,316,736	1,729,777
Noncontrolling interest in consolidated subsidiaries	1,271	$ 1,298
Summit Materials, INC [Member]
Stockholders' Equity/Partners' Interest:
Noncontrolling interest in Summit Materials, Inc.	$ 117,790

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Property, plant and equipment, accumulated depreciation, depletion and amortization	$ 343,087	$ 279,375
Intangible assets, accumulated amortization	$ 4,851	3,073
Common Class A [Member]
Common stock, par value	$ 0.01
Common stock, shares authorized	1,000,000,000
Common stock, shares issued	49,009,738
Common stock, shares outstanding	49,009,738
Common Class B [Member]
Common stock, par value	$ 0.01
Common stock, shares authorized	250,000,000
Common stock, shares issued	69,007,297
Common stock, shares outstanding	69,007,297
Summit Materials, LLC [Member]
Property, plant and equipment, accumulated depreciation, depletion and amortization	$ 343,087	279,375
Intangible assets, accumulated amortization	$ 4,851	$ 3,073

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Revenue:
Product	$ 338,020	$ 258,860	$ 748,210	$ 580,351
Service	88,266	89,276	182,224	196,214
Net revenue	426,286	348,136	930,434	776,565
Delivery and subcontract revenue	45,619	46,623	100,401	93,580
Total revenue	471,905	394,759	1,030,835	870,145
Cost of revenue (excluding items shown separately below):
Product	207,500	176,967	490,923	411,581
Service	59,280	61,907	128,514	140,773
Net cost of revenue	266,780	238,874	619,437	552,354
Delivery and subcontract cost	45,619	46,623	100,401	93,580
Total cost of revenue	312,399	285,497	719,838	645,934
General and administrative expenses	42,539	35,517	149,484	105,872
Depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Transaction costs	304	2,741	8,044	7,737
Operating income (loss)	83,357	47,749	66,651	46,652
Other income, net	(1,171)	(1,408)	(678)	(2,299)
Loss on debt financings	32,641		64,313
Interest expense	20,727	22,085	62,231	62,555
Income (loss) from continuing operations before taxes	31,160	27,072	(59,215)	(13,604)
Income tax benefit	(2,655)	(1,038)	(12,468)	(2,498)
Income (loss) from continuing operations	33,815	28,110	(46,747)	(11,106)
Income from discontinued operations	(57)	(7)	(815)	(356)
Net income (loss)	$ 33,872	28,117	$ (45,932)	(10,750)
Net income per share of Class A common stock:
Basic	$ 0.39		$ 0.14
Diluted	$ 0.39		$ 0.14
Net income (loss)	$ 14,711		$ 4,355
Weighted average shares of Class A common stock:
Diluted	37,963,930		31,811,315
Summit Materials, LLC [Member]
Revenue:
Product	$ 338,020	258,860	$ 748,210	580,351
Service	88,266	89,276	182,224	196,214
Net revenue	426,286	348,136	930,434	776,565
Delivery and subcontract revenue	45,619	46,623	100,401	93,580
Total revenue	471,905	394,759	1,030,835	870,145
Cost of revenue (excluding items shown separately below):
Product	207,500	176,967	490,923	411,581
Service	59,280	61,907	128,514	140,773
Net cost of revenue	266,780	238,874	619,437	552,354
Delivery and subcontract cost	45,619	46,623	100,401	93,580
Total cost of revenue	312,399	285,497	719,838	645,934
General and administrative expenses	42,539	35,517	149,484	105,872
Depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Transaction costs	304	2,741	8,044	7,737
Operating income (loss)	83,357	47,749	66,651	46,652
Other income, net	(1,171)	(1,408)	(678)	(2,299)
Loss on debt financings	32,641		64,313
Interest expense	20,436	22,085	61,649	62,555
Income (loss) from continuing operations before taxes	31,451	27,072	(58,633)	(13,604)
Income tax benefit	(2,655)	(1,038)	(12,468)	(2,498)
Income (loss) from continuing operations	34,106	28,110	(46,165)	(11,106)
Income from discontinued operations	(57)	(7)	(815)	(356)
Net income (loss)	34,163	28,117	(45,350)	(10,750)
Net income (loss) attributable to noncontrolling interest	52	1,243	(1,917)	674
Net income per share of Class A common stock:
Net income (loss)	34,111	26,874	(43,433)	(11,424)
Summit Holdings [Member]
Net income per share of Class A common stock:
Net income (loss)	$ (19,109)	$ (26,874)	$ 48,370	$ 11,424
Common Class A [Member]
Net income per share of Class A common stock:
Basic	$ 0.39		$ 0.14
Diluted	$ 0.39		$ 0.14
Weighted average shares of Class A common stock:
Basic	37,920,452		31,768,406
Diluted	37,963,930		31,811,315

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Net income (loss)	$ 33,872	$ 28,117	$ (45,932)	$ (10,750)
Other comprehensive (loss) income:
Postretirement curtailment adjustment				(1,346)
Postretirement liability adjustment				2,164
Foreign currency translation adjustment	(6,296)	(1,764)	(11,531)	(1,764)
Loss on cash flow hedges	(1,010)		(1,010)
Other comprehensive income (loss)	(7,306)	(1,764)	(12,541)	(946)
Comprehensive income (loss)	26,566	26,353	(58,473)	(11,696)
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC	12,090		1,748
Summit Materials, LLC [Member]
Net income (loss)	34,163	28,117	(45,350)	(10,750)
Other comprehensive (loss) income:
Postretirement curtailment adjustment				(1,346)
Postretirement liability adjustment				2,164
Foreign currency translation adjustment	(6,296)	(1,764)	(11,531)	(1,764)
Loss on cash flow hedges	(1,010)		(1,010)
Other comprehensive income (loss)	(7,306)	(1,764)	(12,541)	(946)
Comprehensive income (loss)	26,857	26,353	(57,891)	(11,696)
Less comprehensive income (loss) attributable to the noncontrolling interest	52	1,243	(1,917)	919
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC	26,805	25,110	(55,974)	(12,615)
Summit Holdings [Member]
Other comprehensive (loss) income:
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC	$ 14,424	$ 25,110	$ (58,304)	$ (12,615)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Cash flow from operating activities:
Net loss	$ (45,932)	$ (10,750)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	90,789	68,467
Share-based compensation expense	18,589	1,746
Deferred income tax benefit		(525)
Net gain on asset disposals	(4,990)	(219)
Net gain on debt financings	(4,570)
Other	136	(463)
(Increase) decrease in operating assets, net of acquisitions:
Accounts receivable, net	(56,287)	(54,463)
Inventories	(3,830)	(3,843)
Costs and estimated earnings in excess of billings	(23,402)	(15,009)
Other current assets	(4,401)	(3,910)
Other assets	(524)	(675)
Increase (decrease) in operating liabilities, net of acquisitions:
Accounts payable	29,383	9,433
Accrued expenses	(12,272)	2,578
Billings in excess of costs and estimated earnings	(763)	270
Other liabilities	(853)	(3,473)
Net cash used in operating activities	(18,927)	(10,836)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(505,466)	(351,941)
Purchases of property, plant and equipment	(69,672)	(64,244)
Proceeds from the sale of property, plant and equipment	8,883	9,575
Other	610	757
Net cash used for investing activities	(565,645)	(405,853)
Cash flow from financing activities:
Proceeds from equity offerings	1,037,444
Capital issuance costs	(61,218)
Capital contributions by partners		24,350
Proceeds from debt issuances	1,415,750	657,217
Debt issuance costs	(10,911)	(8,834)
Payments on debt	(1,251,407)	(258,337)
Purchase of noncontrolling interests	(497,848)
Payments on acquisition-related liabilities	(15,018)	(5,807)
Distributions from partnership	(26,448)
Other		(88)
Net cash provided by (used for) financing activities	590,344	408,501
Net increase (decrease) in cash	5,772	(8,188)
Cash - beginning of period	13,215	18,184
Cash - end of period	18,987	9,996
Summit Materials, LLC [Member]
Cash flow from operating activities:
Net loss	(45,350)	(10,750)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	90,207	68,467
Share-based compensation expense	18,589	1,746
Deferred income tax benefit		(525)
Net gain on asset disposals	(4,990)	(219)
Net gain on debt financings	(4,570)
Other	136	(463)
(Increase) decrease in operating assets, net of acquisitions:
Accounts receivable, net	(56,287)	(54,463)
Inventories	(3,830)	(3,843)
Costs and estimated earnings in excess of billings	(23,402)	(15,009)
Other current assets	(4,401)	(3,910)
Other assets	(524)	(675)
Increase (decrease) in operating liabilities, net of acquisitions:
Accounts payable	29,383	9,433
Accrued expenses	(12,272)	2,578
Billings in excess of costs and estimated earnings	(763)	270
Other liabilities	(853)	(3,473)
Net cash used in operating activities	(18,927)	(10,836)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(505,466)	(351,941)
Purchases of property, plant and equipment	(69,672)	(64,244)
Proceeds from the sale of property, plant and equipment	8,883	9,575
Other	610	757
Net cash used for investing activities	(565,645)	(405,853)
Cash flow from financing activities:
Capital contributions by member	490,916	24,350
Capital issuance costs	(12,539)
Proceeds from debt issuances	1,415,750	657,217
Debt issuance costs	(10,911)	(8,834)
Payments on debt	(1,251,407)	(258,337)
Purchase of noncontrolling interests	(64,100)
Payments on acquisition-related liabilities	(15,018)	(5,807)
Distributions from partnership	(39,952)
Other		(88)
Net cash provided by (used for) financing activities	576,839	408,501
Net increase (decrease) in cash	(7,733)	(8,188)
Cash - beginning of period	13,215	14,917
Cash - end of period	$ 5,482	$ 6,729

Consolidated Statements of Chan

Consolidated Statements of Changes in Redeemable Noncontrolling Interest and Stockholders' Equity /Member's Interest - USD ($) $ in Thousands	Total	Common Class A [Member]	Common Class B [Member]	Noncontrolling Interest [Member]	Accumulated Deficit/Earnings [Member]	Accumulated Other Comprehensive Loss (AOCI) [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Common Class A [Member]	Additional Paid-in Capital [Member]Common Class B [Member]	Redeemable Noncontrolling Interest [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]Noncontrolling Interest [Member]	Summit Materials, LLC [Member]Accumulated Deficit/Earnings [Member]	Summit Materials, LLC [Member]Accumulated Other Comprehensive Loss (AOCI) [Member]	Summit Materials, LLC [Member]Redeemable Noncontrolling Interest [Member]	Summit Materials, LLC [Member]Members Equity [Member]	Summit Materials, LLC [Member]Parent Including Portion Attributable to Non Redeemable Noncontrolling Interest [Member]	Summit Holdings [Member]Partners' Interest [Member]
Beginning Balance at Dec. 28, 2013	$ 286,817									$ 24,767		$ 1,211			$ 24,767			$ 285,606
Beginning Balance at Dec. 28, 2013												1,211	$ (198,511)	$ (6,045)		$ 486,896	$ 283,551
Contributed capital, Summit Materials, Inc	24,350																	24,350
Contributed capital, Summit Materials, LLC																24,350	24,350
Accretion/ redemption value adjustment	(6,211)									6,211			(6,211)		6,211		(6,211)	(6,211)
Net income (loss)	(10,750)									597	$ (10,750)	77	(11,424)		597		(11,347)	(11,424)
Other comprehensive income (loss)	(946)									245	(946)			(1,191)	245		(1,191)	(1,191)
Repurchase of member's interest	88															88	88	88
Share-based compensation	1,750												(1,982)			3,732	1,750	1,750
Ending Balance at Sep. 27, 2014	294,080											1,288						292,792
Ending Balance at Sep. 27, 2014												1,288	(218,128)	(7,236)		514,890	290,814
Ending Balance at Sep. 27, 2014										31,820					31,820
Beginning Balance at Dec. 27, 2014	33,740									33,740	33,740				33,740
Beginning Balance at Dec. 27, 2014											286,983	1,298	(217,416)	(15,546)		518,647	286,983
Beginning Balance at Dec. 27, 2014	286,983											1,298						285,685
Accretion/ redemption value adjustment	(32,252)									32,252								(32,252)
Net income (loss)	(41,415)									(1,890)		(77)						(41,338)
Other comprehensive income (loss)	(5,249)																	(5,249)
Share-based compensation	424																	424
Ending Balance at Mar. 11, 2015	208,491											1,221						207,270
Ending Balance at Mar. 11, 2015										64,102
Beginning Balance at Dec. 27, 2014	33,740									33,740	33,740				33,740
Beginning Balance at Dec. 27, 2014											286,983	1,298	(217,416)	(15,546)		518,647	286,983
Beginning Balance at Dec. 27, 2014	286,983											1,298						285,685
Contributed capital, Summit Materials, LLC																542,479	542,479
Accretion/ redemption value adjustment													(32,252)		(31,850)		(32,252)
Net income (loss)	(45,932)										(45,350)	(27)	(43,433)		$ (1,890)		(43,460)
Other comprehensive income (loss)	(12,541)										(12,541)			(12,541)			(12,541)
Share-based compensation																18,589	18,589
Distributions from partnership																(39,952)	(39,952)
Ending Balance at Sep. 26, 2015	722,193	$ 490	$ 690	$ 117,790	$ 4,355	$ (2,607)	$ 600,204					1,271
Ending Balance at Sep. 26, 2015											719,846	1,271	(293,101)	(28,087)		1,039,763	719,846
Ending Balance, Shares at Sep. 26, 2015		49,009,738	69,007,297
Issuance of common stock, Shares		25,555,555
Recording of noncontrolling interest upon reorganization				207,270														(207,270)
Beginning Balance at Mar. 11, 2015	208,491											1,221						$ 207,270
Net income (loss)	(2,627)			(7,032)	4,355							50
Other comprehensive income (loss)	(7,292)			(4,685)		(2,607)
Share repurchase, Shares			(100)
Purchase of noncontrolling interests	(32,790)	$ 10		(51,315)			18,515			$ 64,102
Purchase of noncontrolling interests, Shares		1,029,183
Share-based compensation	18,165						18,165
Distributions from partnership	(26,448)			(26,448)
Ending Balance at Sep. 26, 2015	722,193	$ 490	$ 690	$ 117,790	$ 4,355	$ (2,607)	$ 600,204					1,271
Ending Balance at Sep. 26, 2015											$ 719,846	$ 1,271	$ (293,101)	$ (28,087)		$ 1,039,763	$ 719,846
Ending Balance, Shares at Sep. 26, 2015		49,009,738	69,007,297
Issuance of common stock, Values	$ 564,694	$ 480	$ 690					$ 564,214	$ (690)
Issuance of common stock, Shares		47,980,555	69,007,397

Summary of Organization and Sig

Summary of Organization and Significant Accounting Policies	9 Months Ended
	Sep. 26, 2015
Summary of Organization and Significant Accounting Policies	1. SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Summit Materials, Inc. (“Summit Inc.” and, together with its subsidiaries, the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mixed concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mixed concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company is organized by geographic region and has three operating segments, which are also its reporting segments: the West; Central; and East regions. Substantially all of the Company’s products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions and to cyclical changes in construction spending, among other factors. On September 23, 2014, Summit Inc. was formed as a Delaware corporation to be a holding company. Its sole material asset is a controlling equity interest in Summit Materials Holdings L.P. (“Summit Holdings”). Pursuant to a reorganization into a holding company structure (the “Reorganization”) consummated in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries and, through Summit Holdings, conducts its business. Together with Summit Inc., certain investment funds affiliated with Blackstone Capital Partners V L.P. and Silverhawk Summit, L.P. (collectively, the “Sponsors”) are the primary owners of Summit Holdings. Initial Public Offering 1 2 Follow-On Offering Basis of Presentation Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 26, 2015, the results of operations for the three and nine months ended September 26, 2015 and September 27, 2014 and cash flows for the nine months ended September 26, 2015 and September 27, 2014. All significant intercompany balances and transactions have been eliminated. The Company’s fiscal year is based on a 52-53 week year with each quarter composed of 13 weeks ending on a Saturday. The 53-week year occurs approximately once every seven years and will occur in 2015. The additional week in the 53-week year will be included in the fourth quarter. The consolidated financial statements of the Company include the accounts of Summit Inc. and its subsidiaries, including noncontrolling interests. As a result of the Reorganization, Summit Holdings became a variable interest entity. Summit Inc. is the primary beneficiary of Summit Holdings as a result of its 100% voting power and control over Summit Holdings and its obligation to absorb losses and its right to receive benefits of Summit Holdings and thus consolidates Summit Holdings in its consolidated financial statements with a corresponding noncontrolling interest elimination of 72.2% between March 11, 2015 and August 11, 2015 and 50.7% between August 8, 2015 and September 26, 2015. Summit Inc.’s August 2015 purchase of 22,425,000 LP Units, 18,675,000 of which were previously held by certain of our pre-IPO owners, decreased the noncontrolling interest’s economic interest from 72.2% to 50.7%. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the IPO and concurrent purchase of the noncontrolling interests of Continental Cement, a 30% redeemable ownership in Continental Cement. Use of Estimates Business and Credit Concentrations— Earnings per Share— Fair Value Measurements— September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897 The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 11.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the derivatives are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material valuation adjustments in the three or nine months ended September 26, 2015 or September 27, 2014. Financial Instruments September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 15,632 15,632 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 39,267 39,267 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet. The fair value of debt was determined based on observable, or Level 2, inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk. Redeemable Noncontrolling Interest New Accounting Standards — Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued a new accounting standard, ASU 2015-04, Practical Expedient for the Measurement Date of an Employer’s Defined Benefit Obligation and Plan Assets In May 2014, the FASB issued a new accounting standard to improve and converge the financial reporting requirements for revenue from contracts with customers. ASU No. 2014-09, Revenue from Contracts with Customers Reclassifications
Summit Materials, LLC [Member]
Summary of Organization and Significant Accounting Policies	1. SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Summit Materials, LLC (“Summit LLC” and, together with its subsidiaries, the “Company”) is a vertically integrated, construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mixed concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mixed concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company is organized by geographic region and has three operating segments, which are also its reporting segments: the West; Central; and East regions. Substantially all of the Company’s products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions and to cyclical changes in construction spending, among other factors. Summit LLC is a wholly owned indirect subsidiary of Summit Materials Holdings L.P. (“Summit Holdings”), whose primary owners are Summit Materials, Inc. (“Summit Inc.”) and certain investment funds affiliated with Blackstone Capital Partners V L.P. and Silverhawk Summit, L.P. (collectively, the “Sponsors”). Summit Inc. was formed as a Delaware corporation on September 23, 2014 to be a holding company. Its sole material asset is a controlling equity interest in Summit Holdings. Pursuant to a reorganization into a holding company structure (the “Reorganization”) in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries, including Summit LLC. Initial Public Offering 1 2 Follow-On Offering Basis of Presentation Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 26, 2015, the results of operations for the three and nine months ended September 26, 2015 and September 27, 2014 and cash flows for the nine months ended September 26, 2015 and September 27, 2014. All significant intercompany balances and transactions have been eliminated. The Company’s fiscal year is based on a 52-53 week year with each quarter composed of 13 weeks ending on a Saturday. The 53-week year occurs approximately once every seven years and will occur in 2015. The additional week in the 53-week year will be included in the fourth quarter. The consolidated financial statements of the Company include the accounts of Summit LLC and its subsidiaries, including noncontrolling interests. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the IPO and concurrent purchase of the noncontrolling interests of Continental Cement, a 30% redeemable ownership in Continental Cement. Use of Estimates Business and Credit Concentrations— Fair Value Measurements— September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897 The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 11.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the derivatives are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material valuation adjustments in the three or nine months ended September 26, 2015 or September 27, 2014. Financial Instruments September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 13,132 13,132 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 30,609 30,609 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet. The fair value of debt was determined based on observable, or Level 2 inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk. Redeemable Noncontrolling Interest New Accounting Standards — Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued a new accounting standard, ASU 2015-04, Practical Expedient for the Measurement Date of an Employer’s Defined Benefit Obligation and Plan Assets, In May 2014, the FASB issued a new accounting standard to improve and converge the financial reporting requirements for revenue from contracts with customers. ASU No. 2014-09, Revenue from Contracts with Customers changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. ASU No. 2014-09 allows for either full retrospective or modified retrospective adoption. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. Early adoption is permitted, but no earlier than 2017. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements. Reclassifications

Reorganization

Reorganization	9 Months Ended
	Sep. 26, 2015
Reorganization	2. REORGANIZATION Prior to the IPO and Reorganization, the capital structure of Summit Holdings consisted of six different classes of limited partnership interests (Class A-1, Class A-2, Class B-1, Class C, Class D-1 and Class D-2), each of which was subject to unique distribution rights. There were no outstanding Class A-2 interests. In connection with the IPO and the Reorganization, the limited partnership agreement of Summit Holdings was amended and restated to, among other things, modify its capital structure by creating the LP Units, referred to as the “Reclassification.” Immediately following the Reclassification, 69,007,297 LP Units were outstanding. In addition, in substitution for part of the economic benefit of the Class C and Class D interests that was not reflected in the conversion of such interests to LP Units, warrants were issued to holders of Class C interests to purchase an aggregate of 160,333 shares of Class A common stock, and options were issued to holders of Class D interests to purchase an aggregate of 4,358,842 shares of Class A common stock (“leverage restoration options”). The exercise price of the warrants and leverage restoration options is the IPO price of $18.00 per share. In conjunction with the Reclassification of the equity-based awards, the Company recognized a $14.5 million modification charge in general and administrative costs. The leverage restoration options were granted under the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the “Omnibus Incentive Plan”). The leverage restoration options that correlate to time-vesting interests vest over four years, beginning on the Reclassification date and the leverage restoration options that correlate to performance-vesting interests vest only when both the relevant return multiple is achieved and a four year time-vesting condition is satisfied. The time-based vesting condition for both the time-vesting and performance-vesting interests will be satisfied with respect to 25% of the performance-vesting options on each of the first four anniversaries of the Reclassification date, subject to the employee’s continued employment through the applicable vesting date. The Company also granted 240,000 options to purchase shares of Class A common stock under the Omnibus Incentive Plan to certain employees some of whom had not previously been granted equity-based interests. These stock options have an exercise price of $18.00 per share, the IPO price, and are subject to a time-based vesting condition that will be satisfied with respect to 25% of the award on each of the first four anniversaries of the grant date, subject to the employee’s continued employment through the applicable vesting date.
Summit Materials, LLC [Member]
Reorganization	2. REORGANIZATION Prior to the IPO and Reorganization, the capital structure of Summit Holdings consisted of six different classes of limited partnership interests (Class A-1, Class A-2, Class B-1, Class C, Class D-1 and Class D-2), each of which was subject to unique distribution rights. There were no outstanding Class A-2 interests. In connection with the IPO and the Reorganization, the limited partnership agreement of Summit Holdings was amended and restated to, among other things, modify its capital structure by creating a single new class of units (the “LP Units”), referred to as the “Reclassification.” Immediately following the Reclassification, 69,007,297 LP Units were outstanding. In addition, in substitution for part of the economic benefit of the Class C and Class D interests that was not reflected in the conversion of such interests to LP Units, warrants were issued to holders of Class C interests to purchase an aggregate of 160,333 shares of Summit Inc.’s Class A common stock, and options were issued to holders of Class D interests to purchase an aggregate of 4,358,842 shares of Summit Inc.’s Class A common stock (“leverage restoration options”). The exercise price of the warrants and leverage restoration options is the IPO price of $18.00 per share. In conjunction with the Reclassification of the equity-based awards, the Company recognized a $14.5 million modification charge in general and administrative costs. The leverage restoration options were granted under the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the “Omnibus Incentive Plan”). The leverage restoration options that correlate to time-vesting interests vest over four years, beginning on the Reclassification date and the leverage restoration options that correlate to performance-vesting interests vest only when both the relevant return multiple is achieved and a four year time-vesting condition is satisfied. The time-based vesting condition for both the time-vesting and performance-vesting interests will be satisfied with respect to 25% of the performance-vesting options on each of the first four anniversaries of the Reclassification date, subject to the employee’s continued employment through the applicable vesting date. The Company also granted 240,000 options to purchase shares of Summit Inc.’s Class A common stock under the Omnibus Incentive Plan to certain employees some of whom had not previously been granted equity-based interests. These stock options have an exercise price of $18.00 per share, the IPO price, and are subject to a time-based vesting condition that will be satisfied with respect to 25% of the award on each of the first four anniversaries of the grant date, subject to the employee’s continued employment through the applicable vesting date.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 26, 2015
Acquisitions	3. ACQUISITIONS On July 17, 2015, the Company acquired the Davenport Assets for a purchase price of $450.0 million in cash and a cement distribution terminal in Bettendorf, Iowa. The operating results of the acquired business have been included in the Central region’s results of operations since the date of the acquisition. Assets acquired and liabilities assumed are measured at their acquisition-date fair value. Goodwill recognized in connection with the acquisition is primarily attributable to the expected profitability, assembled workforce and operational infrastructure of the acquired business and the synergies expected to result after its integration. The Davenport Assets were immediately integrated into the Company’s existing cement operations such that it is not practicable to report revenue and net income separately for the Davenport Assets. Pro Forma Financial Information (unaudited) Three months ended Nine months ended Revenue $ 477,706 $ 1,069,305 Net income 27,649 26,764 The purchase price allocation for the Davenport Assets has not been finalized due to the recent timing of the acquisition. The following table summarizes aggregated information regarding the estimated fair values of the assets acquired and liabilities assumed in conjunction with the acquisition: September 26, 2015 Inventories $ 21,538 Property, plant and equipment 272,815 Other assets 6,537 Financial liabilities (1,509 ) Other long-term liabilities (95 ) Net assets acquired 299,286 Goodwill 150,710 Total consideration 449,996 Transfer of assets (2,182 ) Working capital true-up 896 Net cash paid for acquisitions $ 448,710
Summit Materials, LLC [Member]
Acquisitions	3. ACQUISITIONS On July 17, 2015, the Company acquired the Davenport Assets for a purchase price of $450.0 million in cash and a cement distribution terminal in Bettendorf, Iowa. The operating results of the acquired business have been included in the Central region’s results of operations since the date of the acquisition. Assets acquired and liabilities assumed are measured at their acquisition-date fair value. Goodwill recognized in connection with the acquisition is primarily attributable to the expected profitability, assembled workforces and operational infrastructure of the acquired business and the synergies expected to result after its integration. The Davenport Assets were immediately integrated into the Company’s existing cement operations such that it is not practicable to report revenue and net income separately for the Davenport Assets. Pro Forma Financial Information (unaudited) Three months ended Nine months ended September 26, 2015 September 26, 2015 Revenue $ 477,706 $ 1,069,305 Net income 67,229 24,506 The purchase price allocation for the Davenport Assets has not been finalized due to the recent timing of the acquisition. The following table summarizes aggregated information regarding the estimated fair values of the assets acquired and liabilities assumed in conjunction with the acquisition: September 26, 2015 Inventories $ 21,538 Property, plant and equipment 272,815 Other assets 6,537 Financial liabilities (1,509 ) Other long-term liabilities (95 ) Net assets acquired 299,286 Goodwill 150,710 Total consideration 449,996 Transfer of assets (2,182 ) Working capital true-up 896 Net cash paid for acquisitions $ 448,710

Goodwill

Goodwill	9 Months Ended
	Sep. 26, 2015
Goodwill	4. GOODWILL Changes in the carrying amount of goodwill, by reportable segment, from December 27, 2014 to September 26, 2015 are summarized as follows: West Central East Total Balance, December 27, 2014 $ 297,085 $ 96,025 $ 26,160 $ 419,270 Acquisitions (1) 4,579 150,929 — 155,508 Foreign currency translation adjustments (6,942 ) — — (6,942 ) Balance, September 26, 2015 $ 294,722 $ 246,954 $ 26,160 $ 567,836 (1) Includes certain working capital adjustments related to 2014 acquisitions
Summit Materials, LLC [Member]
Goodwill	4. GOODWILL Changes in the carrying amount of goodwill, by reportable segment, from December 27, 2014 to September 26, 2015 are summarized as follows: West Central East Total Balance, December 27, 2014 $ 297,085 $ 96,025 $ 26,160 $ 419,270 Acquisitions (1) 4,579 150,929 — 155,508 Foreign currency translation adjustments (6,942 ) — — (6,942 ) Balance, September 26, 2015 $ 294,722 $ 246,954 $ 26,160 $ 567,836 (1) Includes certain working capital adjustments related to 2014 acquisitions

Accounts Receivable, Net

Accounts Receivable, Net	9 Months Ended
	Sep. 26, 2015
Accounts Receivable, Net	5. ACCOUNTS RECEIVABLE, NET Accounts receivable, net consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Trade accounts receivable $ 194,235 $ 131,060 Retention receivables 13,396 12,053 Receivables from related parties 705 333 Accounts receivable 208,336 143,446 Less: Allowance for doubtful accounts (2,397 ) (2,144 ) Accounts receivable, net $ 205,939 $ 141,302 Retention receivables are amounts earned by the Company but held by customers until paving and related service contracts and projects are near completion or fully completed. Amounts are expected to be billed and collected within one year.
Summit Materials, LLC [Member]
Accounts Receivable, Net	5. ACCOUNTS RECEIVABLE, NET Accounts receivable, net consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Trade accounts receivable $ 194,235 $ 131,060 Retention receivables 13,396 12,053 Receivables from related parties 705 333 Accounts receivable 208,336 143,446 Less: Allowance for doubtful accounts (2,397 ) (2,144 ) Accounts receivable, net $ 205,939 $ 141,302 Retention receivables are amounts earned by the Company but held by customers until paving and related service contracts and projects are near completion or fully completed. Amounts are expected to be billed and collected within one year.

Inventories

Inventories	9 Months Ended
	Sep. 26, 2015
Inventories	6. INVENTORIES Inventories consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Aggregate stockpiles $ 90,776 $ 88,211 Finished goods 11,284 8,826 Work in process 6,511 1,801 Raw materials 29,465 12,715 Total $ 138,036 $ 111,553
Summit Materials, LLC [Member]
Inventories	6. INVENTORIES Inventories consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Aggregate stockpiles $ 90,776 $ 88,211 Finished goods 11,284 8,826 Work in process 6,511 1,801 Raw materials 29,465 12,715 Total $ 138,036 $ 111,553

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 26, 2015
Accrued Expenses	7. ACCRUED EXPENSES Accrued expenses consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Interest $ 12,973 $ 32,475 Payroll and benefits 22,095 20,326 Capital lease obligations 16,065 17,530 Insurance 13,710 11,402 Non-income taxes 10,221 5,520 Professional fees 1,305 3,299 Other (1) 14,511 10,944 Total $ 90,880 $ 101,496 (1) Consists primarily of subcontractor and working capital settlement accruals.
Summit Materials, LLC [Member]
Accrued Expenses	7. ACCRUED EXPENSES Accrued expenses consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Interest $ 12,973 $ 32,475 Payroll and benefits 22,095 20,326 Capital lease obligations 16,065 17,530 Insurance 13,710 11,402 Non-income taxes 10,221 5,520 Professional fees 1,305 3,299 Other (1) 14,511 10,944 Total $ 90,880 $ 101,496 (1) Consists primarily of subcontractor and working capital settlement accruals.

Debt

Debt	9 Months Ended
	Sep. 26, 2015
Debt	8. DEBT Debt consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Revolving credit facility $ 60,000 $ — Long-term debt: 10 1/2% Senior Notes, due 2020: $153.8 million senior notes, including a $5.5 million net premium at September 26, 2015 and $625.0 million senior notes, including a $26.5 million net premium at December 27, 2014 159,365 651,548 6 1/8% Senior Notes, due 2023: $350.0 million senior notes, issued at par at September 26, 2015 350,000 Term Loan, due 2022: $650.0 million term loan, net of $3.1 million discount at September 26, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014 646,828 413,369 Total 1,156,193 1,064,917 Current portion of long-term debt 8,125 5,275 Long-term debt $ 1,148,068 $ 1,059,642 The contractual payments of long-term debt, including current maturities, for the five years subsequent to September 26, 2015, are as follows: 2015 (three months) $ 3,250 2016 6,500 2017 6,500 2018 4,875 2019 6,500 2020 161,925 Thereafter 964,250 Total 1,153,800 Plus: Original issue net premium 2,393 Total debt $ 1,156,193 Senior Notes The Issuers issued $350.0 million in aggregate principal amount of 6.125% senior notes due July 15, 2023 (the “2023 Notes”) under an indenture dated July 28, 2015 (as amended and supplemented, the “2015 Indenture”). The net proceeds from the 2023 Notes, with proceeds from the refinancing of the term loan described below, were used to pay the $370.0 million initial purchase price for the Davenport Assets and to redeem $183.0 million aggregate principal amount of the 2020 Notes and pay related fees and expenses. The 2015 Indenture contains covenants and events of default generally consistent with the 2012 Indenture. The 2023 Notes were issued at 100% of their par value. Interest on the 2023 Notes is payable semi-annually in arrears on January 15 and July 15 of each year commencing on January 15, 2016. As of September 26, 2015 and December 27, 2014, the Company was in compliance with all covenants under both indentures, as applicable. In April and August 2015, using proceeds from the IPO and the refinancing of the term loan described below, $288.2 million and $183.0 million, respectively, aggregate principal amount of the outstanding 2020 Notes were redeemed at a price equal to par plus an applicable premium. As a result of the redemptions, net charges of $14.1 million and $45.4 million were recognized in the three and nine months ended September 26, 2015, respectively. The fees included $18.2 million and $56.4 million for the applicable prepayment premium and $2.8 million and $7.5 million for the write-off of deferred financing fees, partially offset by $6.9 million and $18.5 million of net benefit from the write-off of the original issuance net premium in the three and nine months ended September 26, 2015, respectively. Senior Secured Credit Facilities On July 17, 2015, Summit LLC refinanced its term loan under the Senior Secured Credit Facilities (the “Refinancing”). The Refinancing, among other things: (i) reduced the applicable margins used to calculate interest rates for term loans under our Senior Secured Credit Facilities to 3.25% for LIBOR rate loans and 2.25% for base rate loans, subject to a LIBOR floor of 1.00% (and one 25 basis point step down upon Summit LLC achieving a certain first lien net leverage ratio); (ii) increased term loans borrowed under our term loan facility from $422.0 million to an aggregate $650.0 million; and (iii) created additional flexibility under the financial maintenance covenants, which are tested quarterly, by increasing the applicable maximum Consolidated First Lien Net Leverage Ratio (as defined in the credit agreement governing the Senior Secured Credit Facilities). On March 11, 2015, Summit LLC entered into Amendment No. 3 to the credit agreement governing the Senior Secured Credit Facilities, which became effective on March 17, 2015 upon the consummation of the IPO. The amendment: (i) increased the size of the revolving credit facility from $150.0 million to $235.0 million; (ii) extended the maturity date of the revolving credit facility to March 11, 2020; (iii) amended certain covenants; and (iv) permits periodic tax distributions as contemplated in a tax receivable agreement, dated as of March 11, 2015, with Summit Holdings. As a result of this amendment, a charge of $0.4 million of deferred financing was recognized in the nine months ended September 26, 2015. The revolving credit facility bears interest per annum equal to, at Summit LLC’s option, either (i) a base rate determined by reference to the highest of (a) the federal funds rate plus 0.50%, (b) the prime rate of Bank of America, N.A. and (c) LIBOR plus 1.00%, plus an applicable margin of 2.0% for base rate loans or (ii) a LIBOR rate determined by reference to Reuters prior to the interest period relevant to such borrowing adjusted for certain additional costs plus an applicable margin of 3.0% for LIBOR rate loans. The interest rate in effect at September 26, 2015 was 3.2%. There were $60.0 million of outstanding borrowings under the revolving credit facility as of September 26, 2015, leaving remaining borrowing capacity of $150.6 million, which is net of $24.4 million of outstanding letters of credit. The outstanding letters of credit are renewed annually and support required bonding on construction projects and the Company’s insurance liabilities. Summit LLC’s Consolidated First Lien Net Leverage Ratio, as such term is defined in the Senior Secured Credit Facilities, should be no greater than 4.75:1.0 as of each quarter-end. As of September 26, 2015 and December 27, 2014, Summit LLC was in compliance with all covenants. Summit LLC’s wholly-owned domestic subsidiary companies, subject to certain exclusions and exceptions, are named as subsidiary guarantors of the 2020 Notes, the 2023 Notes and the Senior Secured Credit Facilities. In addition, Summit LLC has pledged substantially all of its assets as collateral, subject to certain exclusions and exceptions, for the Senior Secured Credit Facilities. Interest expense related to debt totaled $17.8 million and $54.6 million in the three and nine months ended September 26, 2015, respectively, and $19.9 million and $56.4 million in the three and nine months ended September 27, 2014, respectively. The following table presents the activity for the deferred financing fees for the nine months ended September 26, 2015 and September 27, 2014: Deferred financing fees Balance — December 27, 2014 $ 17,215 Loan origination fees 10,911 Amortization (2,731 ) Write off of deferred financing fees (12,135 ) Balance — September 26, 2015 $ 13,260 Balance — December 28, 2013 $ 11,485 Loan origination fees 9,281 Amortization (2,875 ) Balance —September 27, 2014 $ 17,891 Other
Summit Materials, LLC [Member]
Debt	8. DEBT Debt consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Revolving credit facility $ 60,000 $ — Long-term debt: 10 1/2% Senior Notes, due 2020: $153.8 million senior notes, including a $5.5 million net premium at September 26, 2015 and $625.0 million senior notes, including a $26.5 million net premium at December 27, 2014 159,365 651,548 6 1/8% Senior Notes, due 2023: $350.0 million senior notes, issued at par at September 26, 2015 350,000 Term Loan, due 2022: $650.0 million term loan, net of $3.1 million discount at September 26, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014 646,828 413,369 Total 1,156,193 1,064,917 Current portion of long-term debt 8,125 5,275 Long-term debt $ 1,148,068 $ 1,059,642 The contractual payments of long-term debt, including current maturities, for the five years subsequent to September 26, 2015, are as follows: 2015 (three months) $ 3,250 2016 6,500 2017 6,500 2018 4,875 2019 6,500 2020 161,925 Thereafter 964,250 Total 1,153,800 Plus: Original issue net premium 2,393 Total debt $ 1,156,193 Senior Notes The Issuers issued $350.0 million in aggregate principal amount of 6.125% senior notes due July 15, 2023 (the “2023 Notes”) under an indenture dated July 28, 2015 (as amended and supplemented, the “2015 Indenture”). The net proceeds from the 2023 Notes, with proceeds from the refinancing of the term loan described below, were used to pay the $370.0 million initial purchase price for the Davenport Assets and to redeem $183.0 million aggregate principal amount of the 2020 Notes and pay related fees and expenses. The 2015 Indenture contains covenants and events of default generally consistent with the 2012 Indenture. The 2023 Notes were issued at 100% of their par value. Interest on the 2023 Notes is payable semi-annually in arrears on January 15 and July 15 of each year commencing on January 15, 2016. As of September 26, 2015 and December 27, 2014, the Company was in compliance with all covenants under both indentures, as applicable. In April and August 2015, using proceeds from the IPO and the refinancing of the term loan described below, $288.2 million and $183.0 million, respectively, aggregate principal amount of the outstanding 2020 Notes were redeemed at a price equal to par plus an applicable premium. As a result of the redemptions, net charges of $14.1 million and $45.4 million were recognized in the three and nine months ended September 26, 2015, respectively. The fees included $18.2 million and $56.4 million for the applicable prepayment premium and $2.8 million and $7.5 million for the write-off of deferred financing fees, partially offset by $6.9 million and $18.5 million of net benefit from the write-off of the original issuance net premium in the three and nine months ended September 26, 2015, respectively. Senior Secured Credit Facilities On July 17, 2015, Summit LLC refinanced its term loan under the Senior Secured Credit Facilities (the “Refinancing”). The Refinancing, among other things: (i) reduced the applicable margins used to calculate interest rates for term loans under our Senior Secured Credit Facilities to 3.25% for LIBOR rate loans and 2.25% for base rate loans, subject to a LIBOR floor of 1.00% (and one 25 basis point step down upon Summit LLC achieving a certain first lien net leverage ratio); (ii) increased term loans borrowed under our term loan facility from $422.0 million to an aggregate $650.0 million; and (iii) created additional flexibility under the financial maintenance covenants, which are tested quarterly, by increasing the applicable maximum Consolidated First Lien Net Leverage Ratio (as defined in the credit agreement governing the Senior Secured Credit Facilities). On March 11, 2015, Summit LLC entered into Amendment No. 3 to the credit agreement governing the Senior Secured Credit Facilities, which became effective on March 17, 2015 upon the consummation of the IPO. The amendment: (i) increased the size of the revolving credit facility from $150.0 million to $235.0 million; (ii) extended the maturity date of the revolving credit facility to March 11, 2020; (iii) amended certain covenants; and (iv) permits periodic tax distributions as contemplated in a tax receivable agreement, dated as of March 11, 2015, with Summit Holdings. As a result of this amendment, a charge of $0.4 million of deferred financing was recognized in the nine months ended September 26, 2015. The revolving credit facility bears interest per annum equal to, at Summit LLC’s option, either (i) a base rate determined by reference to the highest of (a) the federal funds rate plus 0.50%, (b) the prime rate of Bank of America, N.A. and (c) LIBOR plus 1.00%, plus an applicable margin of 2.5% for base rate loans or (ii) a LIBOR rate determined by reference to Reuters prior to the interest period relevant to such borrowing adjusted for certain additional costs plus an applicable margin of 3.5% for LIBOR rate loans. The interest rate in effect at September 26, 2015 was 3.6%. There were $60.0 million of outstanding borrowings under the revolving credit facility as of September 26, 2015, leaving remaining borrowing capacity of $150.6 million, which is net of $24.4 million of outstanding letters of credit. The outstanding letters of credit are renewed annually and support required bonding on construction projects and the Company’s insurance liabilities. Summit LLC’s Consolidated First Lien Net Leverage Ratio, as such term is defined in the Senior Secured Credit Facilities, should be no greater than 4.75:1.0 as of each quarter-end. As of September 26, 2015 and December 27, 2014, Summit LLC was in compliance with all covenants. Summit LLC’s wholly-owned domestic subsidiary companies, subject to certain exclusions and exceptions, are named as subsidiary guarantors of the 2020 Notes, the 2023 Notes and the Senior Secured Credit Facilities. In addition, Summit LLC has pledged substantially all of its assets as collateral, subject to certain exclusions and exceptions, for the Senior Secured Credit Facilities. Interest expense related to debt totaled $17.8 million and $54.6 million in the three and nine months ended September 26, 2015, respectively, and $19.9 million and $56.4 million in the three and nine months ended September 27, 2014, respectively. The following table presents the activity for the deferred financing fees for the nine months ended September 26, 2015 and September 27, 2014: Deferred financing fees Balance — December 27, 2014 $ 17,215 Loan origination fees 10,911 Amortization (2,731 ) Write off of deferred financing fees (12,135 ) Balance — September 26, 2015 $ 13,260 Balance — December 28, 2013 $ 11,485 Loan origination fees 9,281 Amortization (2,875 ) Balance —September 27, 2014 $ 17,891 Other

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 26, 2015
Accumulated Other Comprehensive Loss	9. ACCUMULATED OTHER COMPREHENSIVE LOSS The changes in each component of accumulated other comprehensive loss consisted of the following: Foreign currency Cash flow hedge Accumulated Balance — December 27, 2014 $ — $ — $ — Foreign currency translation adjustment (2,109 ) — (2,109 ) Loss on cash flow hedges — (498 ) (498 ) Balance — September 26, 2015 $ (2,109 ) $ (498 ) $ (2,607 )
Summit Materials, LLC [Member]
Accumulated Other Comprehensive Loss	9. ACCUMULATED OTHER COMPREHENSIVE LOSS The changes in each component of accumulated other comprehensive loss consisted of the following: Change in Foreign currency Cash flow hedge Accumulated Balance — December 27, 2014 $ (9,730 ) $ (5,816 ) $ — $ (15,546 ) Foreign currency translation adjustment — (11,531 ) — (11,531 ) Loss on cash flow hedges — — (1,010 ) (1,010 ) Balance — September 26, 2015 $ (9,730 ) $ (17,347 ) $ (1,010 ) $ (28,087 ) Balance — December 28, 2013 $ (6,045 ) $ — $ — $ (6,045 ) Postretirement curtailment adjustment (942 ) — — (942 ) Postretirement liability adjustment 1,515 — — 1,515 Foreign currency translation adjustment — (1,764 ) — (1,764 ) Balance —September 27, 2014 $ (5,472 ) $ (1,764 ) $ — $ (7,236 )

Income Taxes

Income Taxes	9 Months Ended
	Sep. 26, 2015
Income Taxes	10. INCOME TAXES Summit Inc.’s tax provision includes its proportional share of Summit Holdings’ tax attributes. Summit Holdings’ subsidiaries are primarily limited liability companies, but do include certain entities organized as C corporations. The tax attributes related to the limited liability companies are passed on to Summit Holdings and then to its partners, including Summit Inc. The tax attributes associated with the C corporation subsidiaries are fully reflected in the Company’s accounts. As of September 26, 2015 and December 27, 2014, Summit Inc. and its subsidiaries had not recognized any liabilities for uncertain tax positions. The Company records interest and penalties as a component of the income tax provision. No material interest or penalties were recognized in income tax expense during the three and nine months ended September 26, 2015 and September 27, 2014. Summit Inc. Valuation Allowance Tax Receivable Agreement Tax Distributions C Corporation Subsidiaries
Summit Materials, LLC [Member]
Income Taxes	10. INCOME TAXES Summit LLC is a limited liability company and passes its tax attributes for federal and state tax purposes to its parent company and is generally not subject to federal or state income tax. However, certain subsidiary entities file federal and state income tax returns due to their status as C corporations. The provision for income taxes is primarily composed of federal, state and local income taxes for the subsidiary entities that have C corporation status. The effective income tax rate for these entities differs from the statutory federal rate primarily due to (1) tax depletion expense in excess of the expense recorded under U.S. GAAP, (2) state income taxes and the effect of graduated tax rates and (3) certain non-recurring items, such as differences in the treatment of transaction costs, which are often not deductible for tax purposes. As of September 26, 2015 and December 27, 2014, the Company has not recognized any liabilities for uncertain tax positions. The Company records interest and penalties as a component of the income tax provision. No material interest or penalties were recognized in income tax expense during the three or nine months ended September 26, 2015 and September 27, 2014. Tax Distributions –

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Net Income Per Share	11. NET INCOME PER SHARE Immediately prior to the consummation of the Company’s IPO, the Company did not have outstanding common stock. In conjunction with the IPO, Summit Inc. sold 25,555,555 shares of Class A shares common stock to the public and issued 1,029,183 shares of Class A common stock in conjunction with the purchase of the noncontrolling interest of Continental Cement. In connection with the follow on offering on August 11, 2015, Summit Inc. sold 22,425,000 shares of Class A common stock to the public, resulting in 49,009,738 shares of Class A common stock outstanding as of September 26, 2015. The 99,342,035 LP Units and 250,000 of outstanding stock options are excluded from the calculations as they would have an antidilutive effect. The following table reconciles basic to diluted loss per share: September 26, 2015 Three months ended Nine months ended Net income attributable to Summit Inc. $ 14,711 $ 4,355 Weighted-average common shares: Weighted average shares of Class A shares 37,920,452 31,768,406 Basic earnings per share $ 0.39 $ 0.14 Weighted average shares of Class A shares 37,920,452 31,768,406 Warrants 43,478 42,909 Weighted average dilutive shares 37,963,930 31,811,315 Diluted earnings per share $ 0.39 $ 0.14 Basic and diluted earnings per share for discontinued operations attributable to Summit Inc. were $0.00 and $0.01 in the three and nine months ended September 26, 2015.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies	12. COMMITMENTS AND CONTINGENCIES The Company is party to certain legal actions arising from the ordinary course of business activities. Accruals are recorded when the outcome is probable and can be reasonably estimated. While the ultimate results of claims and litigation cannot be predicted with certainty, management expects that the ultimate resolution of all pending or threatened claims and litigation will not have a material effect on the Company’s consolidated results of operations, financial position or liquidity. The Company records legal fees as incurred. Litigation and Claims During the ordinary course of business, there may be revisions to project costs and conditions that can give rise to change orders on construction contracts. Revisions can also result in claims made against a customer or subcontractor to recover project variances that have not been satisfactorily addressed through change orders with a customer. The Company had unapproved change orders and claims of $1.2 million in accounts receivable and $3.9 million ($1.2 million in accounts receivable, $0.5 million in costs and estimated earnings in excess of billings and $2.2 million in other assets) as of September 26, 2015 and December 27, 2014, respectively. Environmental Remediation Other
Summit Materials, LLC [Member]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES The Company is party to certain legal actions arising from the ordinary course of business activities. Accruals are recorded when the outcome is probable and can be reasonably estimated. While the ultimate results of claims and litigation cannot be predicted with certainty, management expects that the ultimate resolution of all pending or threatened claims and litigation will not have a material effect on the Company’s consolidated results of operations, financial position or liquidity. The Company records legal fees as incurred. Litigation and Claims During the ordinary course of business, there may be revisions to project costs and conditions that can give rise to change orders on construction contracts. Revisions can also result in claims made against a customer or subcontractor to recover project variances that have not been satisfactorily addressed through change orders with a customer. The Company had unapproved change orders and claims of $1.2 million in accounts receivable and $3.9 million ($1.2 million in accounts receivable, $0.5 million in costs and estimated earnings in excess of billings and $2.2 million in other assets) as of September 26, 2015 and December 27, 2014, respectively. Environmental Remediation Other

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 26, 2015
Supplemental Cash Flow Information	13. SUPPLEMENTAL CASH FLOW INFORMATION Supplemental cash flow information is as follows: Nine months ended September 26, September 27, Cash payments: Interest $ 75,990 $ 59,179 Income taxes 1,516 1,345 Non cash financing activities: Purchase of noncontrolling interest in Continental Cement $ (29,102 ) $ —
Summit Materials, LLC [Member]
Supplemental Cash Flow Information	12. SUPPLEMENTAL CASH FLOW INFORMATION Supplemental cash flow information is as follows: Nine months ended September 26, September 27, 2015 2014 Cash payments: Interest $ 75,990 $ 59,179 Income taxes 1,516 1,345 Non cash financing activities: Purchase of noncontrolling interest in Continental Cement $ (64,102 ) $ —

Segment Information

Segment Information	9 Months Ended
	Sep. 26, 2015
Segment Information	14. SEGMENT INFORMATION The Company has three operating segments, which are its reportable segments: the West; Central; and East regions. These segments are consistent with the Company’s management reporting structure. Each region’s operations consist of various activities related to the production, distribution and sale of construction materials, products and the provision of paving and related services. Assets employed by segment include assets directly identified with those operations. Corporate assets consist primarily of cash, property, plant and equipment for corporate operations and other assets not directly identifiable with a reportable business segment. The accounting policies applicable to each segment are consistent with those used in preparing the consolidated financial statements. The following tables display selected financial data for the Company’s reportable segments: Three months ended Nine months ended September 26, September 27, September 26, September 27, Revenue: West region $ 261,742 $ 211,302 $ 597,484 $ 478,432 Central region 164,084 126,882 338,613 283,541 East region 46,079 56,575 94,738 108,172 Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 Three months ended Nine months ended September 26, September 27, September 26, September 27, Adjusted EBITDA West region $ 59,574 $ 39,105 $ 110,940 $ 71,646 Central region 53,756 30,820 89,984 59,220 East region 13,383 11,868 15,096 10,462 Corporate and other (8,879 ) (9,381 ) (33,577 ) (28,427 ) Total reportable segments and corporate 117,834 72,412 182,443 112,901 Interest expense 20,727 22,085 62,231 62,555 Depreciation, depletion, amortization and accretion 33,306 23,255 86,818 63,950 Initial public offering costs — — 28,296 — Loss on debt financings 32,641 — 64,313 — Income (loss) from continuing operations before taxes $ 31,160 $ 27,072 $ (59,215 ) $ (13,604 ) Nine months ended September 26, September 27, Cash paid for capital expenditures: West region $ 32,192 $ 25,496 Central region 24,335 28,485 East region 9,401 6,590 Total reportable segments 65,928 60,571 Corporate and other 3,744 3,673 Total capital expenditures $ 69,672 $ 64,244 Three months ended Nine months ended September 26, September 27, September 26, September 27, Depreciation, depletion, amortization and accretion: West region $ 13,786 $ 9,155 $ 38,508 $ 23,569 Central region 15,778 9,710 37,198 28,061 East region 3,114 3,984 9,426 11,272 Total reportable segments 32,678 22,849 85,132 62,902 Corporate and other 628 406 1,686 1,048 Total depreciation, depletion, amortization and accretion $ 33,306 $ 23,255 $ 86,818 $ 63,950 September 26, December 27, Total assets: West region $ 866,516 $ 777,981 Central region 1,189,565 704,134 East region 224,720 221,598 Total reportable segments 2,280,801 1,703,713 Corporate and other 49,440 26,064 Total $ 2,330,241 $ 1,729,777 Three months ended Nine months ended September 26, September 27, September 26, September 27, Revenue by product:* Aggregates $ 86,070 $ 68,636 $ 218,336 $ 160,002 Cement 68,481 34,171 110,477 69,435 Ready-mixed concrete 95,481 75,429 254,878 189,198 Asphalt 113,249 104,862 219,492 203,944 Paving and related services 185,092 191,157 366,321 391,925 Other (76,468 ) (79,496 ) (138,669 ) (144,359 ) Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 * Revenue by product includes intercompany and intracompany sales transferred at market value. The elimination of intracompany transactions is included in Other. Revenue from the liquid asphalt terminals is included in asphalt revenue.
Summit Materials, LLC [Member]
Segment Information	13. SEGMENT INFORMATION The Company has three operating segments, which are its reportable segments: the West; Central; and East regions. These segments are consistent with the Company’s management reporting structure. Each region’s operations consist of various activities related to the production, distribution and sale of construction materials, products and the provision of paving and related services. Assets employed by segment include assets directly identified with those operations. Corporate assets consist primarily of cash, property, plant and equipment for corporate operations and other assets not directly identifiable with a reportable business segment. The accounting policies applicable to each segment are consistent with those used in preparing the consolidated financial statements. The following tables display selected financial data for the Company’s reportable segments: Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Revenue: West region $ 261,742 $ 211,302 $ 597,484 $ 478,432 Central region 164,084 126,882 338,613 283,541 East region 46,079 56,575 94,738 108,172 Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Adjusted EBITDA West region $ 59,574 $ 39,105 $ 110,940 $ 71,646 Central region 53,756 30,820 89,984 59,220 East region 13,383 11,868 15,096 10,462 Corporate and other (8,879 ) (9,381 ) (33,577 ) (28,427 ) Total reportable segments and corporate 117,834 72,412 182,443 112,901 Interest expense 20,436 22,085 61,649 62,555 Depreciation, depletion, amortization and accretion 33,306 23,255 86,818 63,950 Initial public offering costs — — 28,296 — Loss on debt financings 32,641 — 64,313 — Income (loss) from continuing operations before taxes $ 31,451 $ 27,072 $ (58,633 ) $ (13,604 ) Nine months ended September 26, September 27, 2015 2014 Cash paid for capital expenditures: West region $ 32,192 $ 25,496 Central region 24,335 28,485 East region 9,401 6,590 Total reportable segments 65,928 60,571 Corporate and other 3,744 3,673 Total capital expenditures $ 69,672 $ 64,244 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Depreciation, depletion, amortization and accretion: West region $ 13,786 $ 9,155 $ 38,508 $ 23,569 Central region 15,778 9,710 37,198 28,061 East region 3,114 3,984 9,426 11,272 Total reportable segments 32,678 22,849 85,132 62,902 Corporate and other 628 406 1,686 1,048 Total depreciation, depletion, amortization and accretion $ 33,306 $ 23,255 $ 86,818 $ 63,950 September 26, December 27, 2015 2014 Total assets: West region $ 866,516 $ 777,981 Central region 1,189,565 704,134 East region 224,720 221,598 Total reportable segments 2,280,801 1,703,713 Corporate and other 35,935 26,064 Total $ 2,316,736 $ 1,729,777 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Revenue by product:* Aggregates $ 86,070 $ 68,636 $ 218,336 $ 160,002 Cement 68,481 34,171 110,477 69,435 Ready-mixed concrete 95,481 75,429 254,878 189,198 Asphalt 113,249 104,862 219,492 203,944 Paving and related services 185,092 191,157 366,321 391,925 Other (76,468 ) (79,496 ) (138,669 ) (144,359 ) Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 * Revenue by product includes intercompany and intracompany sales transferred at market value. The elimination of intracompany transactions is included in Other. Revenue from the liquid asphalt terminals is included in asphalt revenue.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 26, 2015
Related Party Transactions	15. RELATED PARTY TRANSACTIONS Under the terms of a transaction and management fee agreement between Summit Holdings and Blackstone Management Partners L.L.C. (“BMP”), whose affiliates include controlling stockholders of the Company, BMP provided monitoring, advisory and consulting services to the Company through March 17, 2015. Under the terms of the agreement, BMP was permitted to assign, and had assigned, a portion of the fees to which it was entitled to Silverhawk Summit, L.P. and to certain other equity investors. The management fee was calculated based on the greater of $300,000 or 2.0% of the Company’s annual consolidated profit, as defined in the agreement, and is included in general and administrative expenses. The Company incurred management fees totaling $1.0 million during the period between December 28, 2014 and March 17, 2015 and $1.3 million and $2.3 million in the three and nine months ended September 27, 2014, respectively. During these periods, the Company paid immaterial amounts to Silverhawk Summit, L.P. and to other equity investors. Also under the terms of the transaction and management fee agreement, BMP undertook financial and structural analysis, due diligence investigations, corporate strategy and other advisory services and negotiation assistance related to acquisitions for which the Company paid BMP transaction fees equal to 1.0% of the aggregate enterprise value of any acquired entity or, if such transaction was structured as an asset purchase or sale, 1.0% of the consideration paid for or received in respect of the assets acquired or disposed. The Company paid BMP $0.6 million and $2.3 million during the three and nine months ended September 27, 2014, respectively. During these periods, the Company paid immaterial amounts to Silverhawk Summit, L.P. and to other equity investors. The acquisition-related fees paid pursuant to this agreement are included in transaction costs. In connection with the IPO, the transaction and management fee agreement with BMP was terminated on March 17, 2015 for a final payment of $13.8 million; $13.4 million was paid to affiliates of BMP and the remaining $0.4 million was paid to affiliates of Silverhawk Summit, L.P. and to certain other equity investors. In addition to the transaction and management fees paid to BMP, the Company reimburses BMP for direct expenses incurred, which were not material in the three and nine months ended September 26, 2015 and September 27, 2014. On July 17, 2015, the Company purchased the Davenport Assets from Lafarge North America Inc. for $450.0 million in cash and a cement distribution terminal in Bettendorf, Iowa. At closing, $370.0 million of the purchase price was paid, and the remaining $80.0 million was paid on August 13, 2015. Summit Holdings entered into a commitment letter dated April 16, 2015, with Blackstone Capital Partners V L.P. (“BCP”) for equity financing up to $90.0 million in the form of a preferred equity interest (the “Equity Commitment Financing”), which would have been used to pay the $80.0 million deferred purchase price if other financing was not attained by December 31, 2015. For this Equity Commitment Financing, Summit Holdings paid a $1.8 million commitment fee to BCP in the nine months ended September 26, 2015. Blackstone Advisory Partners L.P., an affiliate of BMP, served as an initial purchaser of $5.75 million and $13.0 million principal amount of the 2020 Notes issued in September 2014 and January 2014, respectively, and received compensation in connection therewith. Cement sales to companies owned by a former noncontrolling member of Continental Cement were approximately $1.4 million during the period between December 28, 2014 and March 11, 2015 and $4.7 million and $10.9 million during the three and nine months ended September 27, 2014, respectively. Accounts receivable due from the former noncontrolling member were $0.2 million as of December 27, 2014. In the nine months ended September 27, 2014, the Company made an interest payment of $0.7 million to a certain former noncontrolling member of Continental Cement for a related party note. The principal balance on the note was repaid in 2012. In the nine months ended September 27, 2014, the Company sold certain assets associated with the production of concrete blocks, including inventory and equipment, to a related party for $2.3 million.
Summit Materials, LLC [Member]
Related Party Transactions	14. RELATED PARTY TRANSACTIONS Under the terms of a transaction and management fee agreement between Summit Holdings and Blackstone Management Partners L.L.C. (“BMP”), whose affiliates include controlling stockholders of Summit Inc., BMP provided monitoring, advisory and consulting services to the Company through March 17, 2015. Under the terms of the agreement, BMP was permitted to assign, and had assigned, a portion of the fees to which it was entitled to Silverhawk Summit, L.P. and to certain other equity investors. The management fee was calculated based on the greater of $300,000 or 2.0% of the Company’s annual consolidated profit, as defined in the agreement, and is included in general and administrative expenses. The Company incurred management fees totaling $1.0 million during the period between December 28, 2014 and March 17, 2015 and $1.3 million and $2.3 million in the three and nine months ended September 27, 2014, respectively. During these periods, the Company paid immaterial amounts to Silverhawk Summit, L.P. and to other equity investors. Also under the terms of the transaction and management fee agreement, BMP undertook financial and structural analysis, due diligence investigations, corporate strategy and other advisory services and negotiation assistance related to acquisitions for which the Company paid BMP transaction fees equal to 1.0% of the aggregate enterprise value of any acquired entity or, if such transaction was structured as an asset purchase or sale, 1.0% of the consideration paid for or received in respect of the assets acquired or disposed. The Company paid BMP $0.6 million and $2.3 million during the three and nine months ended September 27, 2014, respectively. During these periods, the Company paid immaterial amounts to Silverhawk Summit, L.P. and to other equity investors. The acquisition-related fees paid pursuant to this agreement are included in transaction costs. In connection with the IPO, the transaction and management fee agreement with BMP was terminated on March 17, 2015 for a final payment of $13.8 million; $13.4 million was paid to affiliates of BMP and the remaining $0.4 million was paid to affiliates of Silverhawk Summit, L.P. and to certain other equity investors. In addition to the transaction and management fees paid to BMP, the Company reimburses BMP for direct expenses incurred, which were not material in the three and nine months ended September 26, 2015 and September 27, 2014. On July 17, 2015, the Company purchased the Davenport Assets from Lafarge North America Inc. for a purchase price of $450.0 million in cash and a cement distribution terminal in Bettendorf, Iowa. At closing, $370.0 million of the purchase price was paid, and the remaining $80.0 million was paid on August 13, 2015. Summit Holdings entered into a commitment letter dated April 16, 2015, with Blackstone Capital Partners V L.P. (“BCP”) for equity financing up to $90.0 million in the form of a preferred equity interest (the “Equity Commitment Financing”), which would have been used to pay the $80.0 million deferred purchase price if other financing was not attained by December 31, 2015. For the Equity Commitment Financing, the Company paid a $1.8 million commitment fee to BCP in the nine months ended September 26, 2015. Blackstone Advisory Partners L.P., an affiliate of BMP, served as an initial purchaser of $5.75 million and $13.0 million principal amount of the 2020 Notes issued in September 2014 and January 2014, respectively, and received compensation in connection therewith. Cement sales to companies owned by a former noncontrolling member of Continental Cement were approximately $1.4 million during the period between December 28, 2014 and March 11, 2015 and $4.7 million and $10.9 million during the three and nine months ended September 27, 2014, respectively. Accounts receivable due from the former noncontrolling member were $0.2 million as of December 27, 2014. In the nine months ended September 27, 2014, the Company made an interest payment of $0.7 million to a certain former noncontrolling member of Continental Cement for a related party note. The principal balance on the note was repaid in 2012. In the nine months ended September 27, 2014, the Company sold certain assets associated with the production of concrete blocks, including inventory and equipment, to a related party for $2.3 million.

Guarantor and Non-Guarantor Fin

Guarantor and Non-Guarantor Financial Information	9 Months Ended
	Sep. 26, 2015
Summit Materials, LLC [Member]
Guarantor and Non-Guarantor Financial Information	15. GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION Summit LLC’s domestic wholly-owned subsidiary companies other than Finance Corp. are named as guarantors (collectively, the “Guarantors”) of the 2020 Notes and the 2023 Notes (collectively, the “Senior Notes”). Certain other partially-owned subsidiaries and a non-U.S. entity do not guarantee the Senior Notes (collectively, the “Non-Guarantors”). The Guarantors provide a joint and several, full and unconditional guarantee of the Senior Notes. There are no significant restrictions on Summit LLC’s ability to obtain funds from any of the Guarantor Subsidiaries in the form of dividends or loans. Additionally, there are no significant restrictions on a Guarantor Subsidiary’s ability to obtain funds from Summit LLC or its direct or indirect subsidiaries. The following condensed consolidating balance sheets, statements of operations and cash flows are provided for the Issuers, the Wholly-owned Guarantors and the Non-Guarantors. On March 17, 2015, the noncontrolling interests of Continental Cement were purchased resulting in Continental Cement being a wholly-owned indirect subsidiary of Summit LLC. Continental Cement’s results of operations and cash flows are reflected with the Guarantors for the three and nine months ended September 26, 2015. In 2014, Continental Cement’s results are shown separately as a Non Wholly-owned Guarantor. Earnings from subsidiaries are included in other income in the condensed consolidated statements of operations below. The financial information may not necessarily be indicative of the financial position, results of operations or cash flows had the guarantor or non-guarantor subsidiaries operated as independent entities. Condensed Consolidating Balance Sheets September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 8,989 $ 1,025 $ 8,130 $ (12,662 ) $ 5,482 Accounts receivable, net — 195,120 11,163 (344 ) 205,939 Intercompany receivables 1,322,050 14,869 8,996 (1,345,915 ) — Cost and estimated earnings in excess of billings — 33,447 728 — 34,175 Inventories — 132,734 5,302 — 138,036 Other current assets 1,088 19,319 1,355 — 21,762 Total current assets 1,332,127 396,514 35,674 (1,358,921 ) 405,394 Property, plant and equipment, net 9,433 1,240,126 26,668 — 1,276,227 Goodwill — 519,759 48,077 — 567,836 Intangible assets, net — 14,044 1,437 — 15,481 Other assets 881,923 132,532 1,271 (963,928 ) 51,798 Total assets $ 2,223,483 $ 2,302,975 $ 113,127 $ (2,322,849 ) $ 2,316,736 Liabilities, Redeemable Noncontrolling Interest and Member’s Interest Current liabilities: Current portion of debt $ 68,125 $ — $ — $ — $ 68,125 Current portion of acquisition-related liabilities — 17,691 — — 17,691 Accounts payable 7,436 102,571 3,563 (344 ) 113,226 Accrued expenses 30,998 70,386 2,158 (12,662 ) 90,880 Intercompany payables 67,671 1,274,510 3,734 (1,345,915 ) — Billings in excess of costs and estimated earnings — 10,983 22 — 11,005 Total current liabilities 174,230 1,476,141 9,477 (1,358,921 ) 300,927 Long-term debt 1,148,068 61,377 — (61,377 ) 1,148,068 Acquisition-related liabilities — 33,320 — — 33,320 Other noncurrent liabilities 1,558 110,856 57,268 (55,107 ) 114,575 Total liabilities 1,323,856 1,681,694 66,745 (1,475,405 ) 1,596,890 Redeemable noncontrolling interest — — — — — Redeemable members’ interest — — — — — Total stockholders’ equity/partners’ interest 899,627 621,281 46,382 (847,444 ) 719,846 Total liabilities, redeemable noncontrolling interest and member’s interest $ 2,223,483 $ 2,302,975 $ 113,127 $ (2,322,849 ) $ 2,316,736 Condensed Consolidating Balance Sheets December 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- inations Consol- idated Assets Current assets: Cash and cash equivalents $ 10,837 $ 2 $ 695 $ 8,793 $ (7,112 ) $ 13,215 Accounts receivable, net 1 6,629 124,380 11,525 (1,233 ) 141,302 Intercompany receivables 376,344 4,095 30,539 4,052 (415,030 ) — Cost and estimated earnings in excess of billings — — 9,819 355 — 10,174 Inventories — 8,696 98,188 4,669 — 111,553 Other current assets 7,148 464 9,638 1,775 (1,853 ) 17,172 Total current assets 394,330 19,886 273,259 31,169 (425,228 ) 293,416 Property, plant and equipment, net 7,035 302,524 610,717 30,325 — 950,601 Goodwill — 23,124 340,969 55,177 — 419,270 Intangible assets, net — 542 14,245 2,860 — 17,647 Other assets 1,153,204 25,233 125,462 1,362 (1,256,418 ) 48,843 Total assets $ 1,554,569 $ 371,309 $ 1,364,652 $ 120,893 $ (1,681,646 ) $ 1,729,777 Liabilities, Redeemable Noncontrolling Interest and Member’s Interest Current liabilities: Current portion of debt $ 5,275 $ 1,273 $ 3,990 $ — $ (5,263 ) $ 5,275 Current portion of acquisition-related liabilities 166 — 18,236 — — 18,402 Accounts payable 3,655 6,845 65,018 4,569 (1,233 ) 78,854 Accrued expenses 37,101 10,178 59,477 3,705 (8,965 ) 101,496 Intercompany payables 162,728 4,052 245,416 2,834 (415,030 ) — Billings in excess of costs and estimated earnings — — 8,931 27 — 8,958 Total current liabilities 208,925 22,348 401,068 11,135 (430,491 ) 212,985 Long-term debt 1,059,642 153,318 480,599 — (633,917 ) 1,059,642 Acquisition-related liabilities — — 42,736 — — 42,736 Other noncurrent liabilities 796 24,787 65,479 57,736 (55,107 ) 93,691 Total liabilities 1,269,363 200,453 989,882 68,871 (1,119,515 ) 1,409,054 Redeemable noncontrolling interest — — — — 33,740 33,740 Redeemable members’ interest — 34,543 — — (34,543 ) — Total stockholders’ equity/partners’ interest 285,206 136,313 374,770 52,022 (561,328 ) 286,983 Total liabilities, redeemable noncontrolling interest and member’s interest $ 1,554,569 $ 371,309 $ 1,364,652 $ 120,893 $ (1,681,646 ) $ 1,729,777 Condensed Consolidating Statements of Operations For the three months ended September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Revenue $ — $ 454,501 $ 21,472 $ (4,068 ) $ 471,905 Cost of revenue (excluding items shown separately below) — 304,204 12,263 (4,068 ) 312,399 General and administrative expenses 8,881 32,362 1,600 — 42,843 Depreciation, depletion, amortization and accretion 628 31,374 1,304 — 33,306 Operating (loss) income (9,509 ) 86,561 6,305 — 83,357 Other (income) expense, net (58,666 ) 3,639 (17 ) 86,514 31,470 Interest expense 15,046 15,286 900 (10,796 ) 20,436 Income from continuing operations before taxes 34,111 67,636 5,422 (75,718 ) 31,451 Income tax benefit (expense) — (2,690 ) 35 — (2,655 ) Income from continuing operations 34,111 70,326 5,387 (75,718 ) 34,106 Income from discontinued operations — (57 ) — — (57 ) Net income 34,111 70,383 5,387 (75,718 ) 34,163 Net income attributable to minority interest — — — 52 52 Net income attributable to member of Summit Materials, LLC $ 34,111 $ 70,383 $ 5,387 $ (75,770 ) $ 34,111 Comprehensive income attributable to member of Summit Materials, LLC $ 26,805 $ 69,373 $ (909 ) $ (68,464 ) $ 26,805 Condensed Consolidating Statements of Operations For the three months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Revenue $ — $ 34,171 $ 348,785 $ 22,626 $ (10,823 ) $ 394,759 Cost of revenue (excluding items shown separately below) — 25,603 253,284 17,433 (10,823 ) 285,497 General and administrative expenses 8,694 1,651 27,418 495 — 38,258 Depreciation, depletion, amortization and accretion 406 3,708 18,618 523 — 23,255 Operating (loss) income (9,100 ) 3,209 49,465 4,175 — 47,749 Other (income) expense, net (43,887 ) (945 ) (2,679 ) (16 ) 46,119 (1,408 ) Interest expense 7,913 2,931 13,416 233 (2,408 ) 22,085 Income from continuing operations before taxes 26,874 1,223 38,728 3,958 (43,711 ) 27,072 Income tax benefit (expense) — — (1,038 ) — — (1,038 ) Income from continuing operations 26,874 1,223 39,766 3,958 (43,711 ) 28,110 Income from discontinued operations — — (7 ) — — (7 ) Net income 26,874 1,223 39,773 3,958 (43,711 ) 28,117 Net income attributable to minority interest — — — — 1,243 1,243 Net income attributable to member of Summit Materials, LLC $ 26,874 $ 1,223 $ 39,773 $ 3,958 $ (44,954 ) $ 26,874 Comprehensive income attributable to member of Summit Materials, LLC $ 25,110 $ 1,223 $ 39,773 $ 2,194 $ (43,190 ) $ 25,110 Condensed Consolidating Statements of Operations For the nine months ended September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Revenue $ — $ 980,153 $ 78,821 $ (28,139 ) $ 1,030,835 Cost of revenue (excluding items shown separately below) — 696,068 51,909 (28,139 ) 719,838 General and administrative expenses 61,634 90,959 4,935 — 157,528 Depreciation, depletion, amortization and accretion 1,686 80,997 4,135 — 86,818 Operating (loss) income (63,320 ) 112,129 17,842 — 66,651 Other (income) expense, net (55,083 ) 7,140 142 111,436 63,635 Interest expense 35,196 45,332 2,689 (21,568 ) 61,649 Income from continuing operations before taxes (43,433 ) 59,657 15,011 (89,868 ) (58,633 ) Income tax benefit (expense) — (12,852 ) 384 — (12,468 ) Income from continuing operations (43,433 ) 72,509 14,627 (89,868 ) (46,165 ) Income from discontinued operations — (815 ) — — (815 ) Net income (43,433 ) 73,324 14,627 (89,868 ) (45,350 ) Net income attributable to minority interest — — — (1,917 ) (1,917 ) Net income attributable to member of Summit Materials, LLC $ (43,433 ) $ 73,324 $ 14,627 $ (87,951 ) $ (43,433 ) Comprehensive income attributable to member of Summit Materials, LLC $ (55,974 ) $ 72,314 $ 3,096 $ (75,410 ) $ (55,974 ) Condensed Consolidating Statements of Operations For the nine months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Revenue $ — $ 69,435 $ 776,502 $ 43,900 $ (19,692 ) $ 870,145 Cost of revenue (excluding items shown separately below) — 53,229 581,602 30,795 (19,692 ) 645,934 General and administrative expenses 26,384 5,225 80,938 1,062 — 113,609 Depreciation, depletion, amortization and accretion 1,047 10,484 51,351 1,068 — 63,950 Operating (loss) income (27,431 ) 497 62,611 10,975 — 46,652 Other expense (income), net (36,161 ) (2,303 ) (4,233 ) 29 40,369 (2,299 ) Interest expense 21,581 8,788 37,831 289 (5,934 ) 62,555 (Loss) income from continuing operations before taxes (12,851 ) (5,988 ) 29,013 10,657 (34,435 ) (13,604 ) Income tax benefit (1,427 ) — (1,071 ) — — (2,498 ) (Loss) income from continuing operations (11,424 ) (5,988 ) 30,084 10,657 (34,435 ) (11,106 ) Income from discontinued operations — — (356 ) — — (356 ) Net (loss) income (11,424 ) (5,988 ) 30,440 10,657 (34,435 ) (10,750 ) Net loss attributable to noncontrolling interest — — — — 674 674 Net (loss) income attributable to member of Summit Materials, LLC $ (11,424 ) $ (5,988 ) $ 30,440 $ 10,657 $ (35,109 ) $ (11,424 ) Comprehensive (loss) income attributable to member of Summit Materials, LLC $ (12,615 ) (5,170 ) $ 30,440 $ 8,893 $ (34,163 ) $ (12,615 ) Condensed Consolidating Statements of Cash Flows For the nine months ended September 26, 2015 Issuers Wholly- Non- Elim- Consol- Net cash (used in) provided by operating activities $ (140,504 ) $ 112,541 $ 9,203 $ (167 ) $ (18,927 ) Cash flow from investing activities: Acquisitions, net of cash acquired — (505,466 ) — — (505,466 ) Purchase of property, plant and equipment (3,743 ) (65,001 ) (928 ) — (69,672 ) Proceeds from the sale of property, plant, and equipment — 8,821 62 — 8,883 Other — 610 — — 610 Net cash used for investing activities (3,743 ) (561,036 ) (866 ) — (565,645 ) Cash flow from financing activities: Proceeds from investment by member 490,916 — — — 490,916 Capital issuance costs (12,539 ) — — — (12,539 ) Net proceeds from debt issuance 1,415,750 — — — 1,415,750 Loans received from and payments made on loans from other Summit Companies (1,031,576 ) 1,047,015 (9,000 ) (6,439 ) — Payments on long-term debt (669,123 ) (583,340 ) — 1,056 (1,251,407 ) Payments on acquisition-related liabilities (166 ) (14,852 ) — — (15,018 ) Financing costs (10,911 ) — — — (10,911 ) Distributions from partnership (39,952 ) — — — (39,952 ) Other — — — — — Net cash provided by (used for) financing activities 142,399 448,823 (9,000 ) (5,383 ) 576,839 Net increase (decrease) in cash (1,848 ) 328 (663 ) (5,550 ) (7,733 ) Cash — Beginning of period 10,837 697 8,793 (7,112 ) 13,215 Cash— End of period $ 8,989 $ 1,025 $ 8,130 $ (12,662 ) $ 5,482 Condensed Consolidating Statements of Cash Flows For the nine months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Net cash used in operating activities $ (36,504 ) $ (2,408 ) $ 28,727 $ 668 $ (1,319 ) $ (10,836 ) Cash flow from investing activities: Acquisitions, net of cash acquired (181,754 ) — (170,187 ) — — (351,941 ) Purchase of property, plant and equipment (3,674 ) (13,472 ) (46,575 ) (523 ) — (64,244 ) Proceeds from the sale of property, plant, and equipment — — 9,345 230 — 9,575 Other — — (409 ) — 1,166 757 Net cash (used for) provided by investing activities (185,428 ) (13,472 ) (207,826 ) (293 ) 1,166 (405,853 ) Cash flow from financing activities: Proceeds from investment by member 24,350 — — 1,353 (1,353 ) 24,350 Net proceeds from debt issuance 657,217 — — — — 657,217 Loans received from and payments made on loans from other Summit Companies (195,590 ) 16,383 189,243 (2,113 ) (7,923 ) — Payments on long-term debt (251,062 ) (509 ) (6,766 ) — — (258,337 ) Payments on acquisition-related liabilities (1,500 ) — (4,307 ) — — (5,807 ) Financing costs (8,834 ) — — — — (8,834 ) Other (88 ) — (1,500 ) — 1,500 (88 ) Net cash provided by (used for) financing activities 224,493 15,874 176,670 (760 ) (7,776 ) 408,501 Net increase (decrease) in cash 2,561 (6 ) (2,429 ) (385 ) (7,929 ) (8,188 ) Cash — Beginning of period 10,375 9 3,442 3,631 (2,540 ) 14,917 Cash— End of period $ 12,936 $ 3 $ 1,013 $ 3,246 $ (10,469 ) $ 6,729

Summary of Organization and S24

Summary of Organization and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 26, 2015
Initial Public Offering	Initial Public Offering 1 2
Follow-On Offering	Follow-On Offering
Basis of Presentation	Basis of Presentation Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 26, 2015, the results of operations for the three and nine months ended September 26, 2015 and September 27, 2014 and cash flows for the nine months ended September 26, 2015 and September 27, 2014. All significant intercompany balances and transactions have been eliminated. The Company’s fiscal year is based on a 52-53 week year with each quarter composed of 13 weeks ending on a Saturday. The 53-week year occurs approximately once every seven years and will occur in 2015. The additional week in the 53-week year will be included in the fourth quarter. The consolidated financial statements of the Company include the accounts of Summit Inc. and its subsidiaries, including noncontrolling interests. As a result of the Reorganization, Summit Holdings became a variable interest entity. Summit Inc. is the primary beneficiary of Summit Holdings as a result of its 100% voting power and control over Summit Holdings and its obligation to absorb losses and its right to receive benefits of Summit Holdings and thus consolidates Summit Holdings in its consolidated financial statements with a corresponding noncontrolling interest elimination of 72.2% between March 11, 2015 and August 11, 2015 and 50.7% between August 8, 2015 and September 26, 2015. Summit Inc.’s August 2015 purchase of 22,425,000 LP Units, 18,675,000 of which were previously held by certain of our pre-IPO owners, decreased the noncontrolling interest’s economic interest from 72.2% to 50.7%. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the IPO and concurrent purchase of the noncontrolling interests of Continental Cement, a 30% redeemable ownership in Continental Cement.
Use of Estimates	Use of Estimates
Business and Credit Concentrations	Business and Credit Concentrations—
Earnings per Share	Earnings per Share—
Fair Value Measurements	Fair Value Measurements— September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897 The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 11.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the derivatives are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material valuation adjustments in the three or nine months ended September 26, 2015 or September 27, 2014.
Financial Instruments	Financial Instruments September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 15,632 15,632 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 39,267 39,267 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet. The fair value of debt was determined based on observable, or Level 2, inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interest
New Accounting Standards	New Accounting Standards — Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued a new accounting standard, ASU 2015-04, Practical Expedient for the Measurement Date of an Employer’s Defined Benefit Obligation and Plan Assets In May 2014, the FASB issued a new accounting standard to improve and converge the financial reporting requirements for revenue from contracts with customers. ASU No. 2014-09, Revenue from Contracts with Customers
Reclassifications	Reclassifications
Summit Materials, LLC [Member]
Initial Public Offering	Initial Public Offering 1 2
Follow-On Offering	Follow-On Offering
Basis of Presentation	Basis of Presentation Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 26, 2015, the results of operations for the three and nine months ended September 26, 2015 and September 27, 2014 and cash flows for the nine months ended September 26, 2015 and September 27, 2014. All significant intercompany balances and transactions have been eliminated. The Company’s fiscal year is based on a 52-53 week year with each quarter composed of 13 weeks ending on a Saturday. The 53-week year occurs approximately once every seven years and will occur in 2015. The additional week in the 53-week year will be included in the fourth quarter. The consolidated financial statements of the Company include the accounts of Summit LLC and its subsidiaries, including noncontrolling interests. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the IPO and concurrent purchase of the noncontrolling interests of Continental Cement, a 30% redeemable ownership in Continental Cement.
Use of Estimates	Use of Estimates
Business and Credit Concentrations	Business and Credit Concentrations—
Fair Value Measurements	Fair Value Measurements— September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897 The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 11.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the derivatives are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material valuation adjustments in the three or nine months ended September 26, 2015 or September 27, 2014.
Financial Instruments	Financial Instruments September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 13,132 13,132 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 30,609 30,609 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet. The fair value of debt was determined based on observable, or Level 2 inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interest
New Accounting Standards	New Accounting Standards — Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued a new accounting standard, ASU 2015-04, Practical Expedient for the Measurement Date of an Employer’s Defined Benefit Obligation and Plan Assets, In May 2014, the FASB issued a new accounting standard to improve and converge the financial reporting requirements for revenue from contracts with customers. ASU No. 2014-09, Revenue from Contracts with Customers changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. ASU No. 2014-09 allows for either full retrospective or modified retrospective adoption. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. Early adoption is permitted, but no earlier than 2017. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements.
Reclassifications	Reclassifications

Summary of Organization and S25

Summary of Organization and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 26, 2015
Schedule of Contingent Consideration Obligations Measured at Fair Value	The fair value of contingent consideration and derivatives as of September 26, 2015 and December 27, 2014 was: September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of September 26, 2015 and December 27, 2014 was: September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 15,632 15,632 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 39,267 39,267 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet.
Summit Materials, LLC [Member]
Schedule of Contingent Consideration Obligations Measured at Fair Value	The fair value of contingent consideration and derivatives as of September 26, 2015 and December 27, 2014 was: September 26, 2015 December 27, 2014 Current portion of derivatives and acquisition-related liabilities: Contingent consideration $ 4,559 $ 2,375 Cash flow hedge 114 Derivatives and acquisition- related liabilities: Contingent consideration $ 2,711 $ 5,379 Cash flow hedge 897
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of September 26, 2015 and December 27, 2014 was: September 26, 2015 December 27, 2014 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt (1) $ 1,155,557 $ 1,156,193 $ 1,101,873 $ 1,064,917 Level 3 Current portion of deferred consideration and noncompete obligations (2) 13,132 13,132 16,027 16,027 Long term portion of deferred consideration and noncompete obligations (3) 30,609 30,609 37,357 37,357 (1) $8.1 million and $5.3 million included in current portion of debt as of September 26, 2015 and December 27, 2014, respectively. Excludes $60.0 million outstanding on the revolving credit facility as of September 26, 2015. (2) Included in current portion of acquisition-related liabilities on the balance sheet. (3) Included in acquisition-related liabilities on the balance sheet.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 26, 2015
Summary of Proforma Information	The following unaudited supplemental pro forma information presents the financial results as if the Davenport Assets had been acquired on the first day of the 2014 fiscal year. This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on the first day of the preceding fiscal year, nor is it indicative of any future results. The pro forma adjustments include a reduction of transaction costs of $6.5 million and additional depreciation, depletion, amortization and accretion of $7.5 million. Three months ended Nine months ended Revenue $ 477,706 $ 1,069,305 Net income 27,649 26,764
Summary of Assets Acquired and Liabilities Assumed	The purchase price allocation for the Davenport Assets has not been finalized due to the recent timing of the acquisition. The following table summarizes aggregated information regarding the estimated fair values of the assets acquired and liabilities assumed in conjunction with the acquisition: September 26, 2015 Inventories $ 21,538 Property, plant and equipment 272,815 Other assets 6,537 Financial liabilities (1,509 ) Other long-term liabilities (95 ) Net assets acquired 299,286 Goodwill 150,710 Total consideration 449,996 Transfer of assets (2,182 ) Working capital true-up 896 Net cash paid for acquisitions $ 448,710
Summit Materials, LLC [Member]
Summary of Proforma Information	The following unaudited supplemental pro forma information presents the financial results as if the Davenport Assets had been acquired on the first day of the 2014 fiscal year. This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on the first day of the preceding fiscal year, nor is it indicative of any future results. The pro forma adjustments include a reduction of transaction costs of $6.5 million and additional depreciation, depletion, amortization and accretion of $7.5 million. Three months ended Nine months ended September 26, 2015 September 26, 2015 Revenue $ 477,706 $ 1,069,305 Net income 67,229 24,506
Summary of Assets Acquired and Liabilities Assumed	The following table summarizes aggregated information regarding the estimated fair values of the assets acquired and liabilities assumed in conjunction with the acquisition: September 26, 2015 Inventories $ 21,538 Property, plant and equipment 272,815 Other assets 6,537 Financial liabilities (1,509 ) Other long-term liabilities (95 ) Net assets acquired 299,286 Goodwill 150,710 Total consideration 449,996 Transfer of assets (2,182 ) Working capital true-up 896 Net cash paid for acquisitions $ 448,710

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 26, 2015
Summary of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill, by reportable segment, from December 27, 2014 to September 26, 2015 are summarized as follows: West Central East Total Balance, December 27, 2014 $ 297,085 $ 96,025 $ 26,160 $ 419,270 Acquisitions (1) 4,579 150,929 — 155,508 Foreign currency translation adjustments (6,942 ) — — (6,942 ) Balance, September 26, 2015 $ 294,722 $ 246,954 $ 26,160 $ 567,836 (1) Includes certain working capital adjustments related to 2014 acquisitions
Summit Materials, LLC [Member]
Summary of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill, by reportable segment, from December 27, 2014 to September 26, 2015 are summarized as follows: West Central East Total Balance, December 27, 2014 $ 297,085 $ 96,025 $ 26,160 $ 419,270 Acquisitions (1) 4,579 150,929 — 155,508 Foreign currency translation adjustments (6,942 ) — — (6,942 ) Balance, September 26, 2015 $ 294,722 $ 246,954 $ 26,160 $ 567,836 (1) Includes certain working capital adjustments related to 2014 acquisitions

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	9 Months Ended
	Sep. 26, 2015
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Trade accounts receivable $ 194,235 $ 131,060 Retention receivables 13,396 12,053 Receivables from related parties 705 333 Accounts receivable 208,336 143,446 Less: Allowance for doubtful accounts (2,397 ) (2,144 ) Accounts receivable, net $ 205,939 $ 141,302
Summit Materials, LLC [Member]
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Trade accounts receivable $ 194,235 $ 131,060 Retention receivables 13,396 12,053 Receivables from related parties 705 333 Accounts receivable 208,336 143,446 Less: Allowance for doubtful accounts (2,397 ) (2,144 ) Accounts receivable, net $ 205,939 $ 141,302

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 26, 2015
Components of Inventories	Inventories consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Aggregate stockpiles $ 90,776 $ 88,211 Finished goods 11,284 8,826 Work in process 6,511 1,801 Raw materials 29,465 12,715 Total $ 138,036 $ 111,553
Summit Materials, LLC [Member]
Components of Inventories	Inventories consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Aggregate stockpiles $ 90,776 $ 88,211 Finished goods 11,284 8,826 Work in process 6,511 1,801 Raw materials 29,465 12,715 Total $ 138,036 $ 111,553

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 26, 2015
Components of Accrued Expenses	Accrued expenses consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Interest $ 12,973 $ 32,475 Payroll and benefits 22,095 20,326 Capital lease obligations 16,065 17,530 Insurance 13,710 11,402 Non-income taxes 10,221 5,520 Professional fees 1,305 3,299 Other (1) 14,511 10,944 Total $ 90,880 $ 101,496 (1) Consists primarily of subcontractor and working capital settlement accruals.
Summit Materials, LLC [Member]
Components of Accrued Expenses	Accrued expenses consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Interest $ 12,973 $ 32,475 Payroll and benefits 22,095 20,326 Capital lease obligations 16,065 17,530 Insurance 13,710 11,402 Non-income taxes 10,221 5,520 Professional fees 1,305 3,299 Other (1) 14,511 10,944 Total $ 90,880 $ 101,496 (1) Consists primarily of subcontractor and working capital settlement accruals.

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 26, 2015
Schedule of Debt	Debt consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, Revolving credit facility $ 60,000 $ — Long-term debt: 10 1/2% Senior Notes, due 2020: $153.8 million senior notes, including a $5.5 million net premium at September 26, 2015 and $625.0 million senior notes, including a $26.5 million net premium at December 27, 2014 159,365 651,548 6 1/8% Senior Notes, due 2023: $350.0 million senior notes, issued at par at September 26, 2015 350,000 Term Loan, due 2022: $650.0 million term loan, net of $3.1 million discount at September 26, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014 646,828 413,369 Total 1,156,193 1,064,917 Current portion of long-term debt 8,125 5,275 Long-term debt $ 1,148,068 $ 1,059,642
Schedule of Contractual Payments of Long-Term Debt	The contractual payments of long-term debt, including current maturities, for the five years subsequent to September 26, 2015, are as follows: 2015 (three months) $ 3,250 2016 6,500 2017 6,500 2018 4,875 2019 6,500 2020 161,925 Thereafter 964,250 Total 1,153,800 Plus: Original issue net premium 2,393 Total debt $ 1,156,193
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the nine months ended September 26, 2015 and September 27, 2014: Deferred financing fees Balance — December 27, 2014 $ 17,215 Loan origination fees 10,911 Amortization (2,731 ) Write off of deferred financing fees (12,135 ) Balance — September 26, 2015 $ 13,260 Balance — December 28, 2013 $ 11,485 Loan origination fees 9,281 Amortization (2,875 ) Balance —September 27, 2014 $ 17,891
Summit Materials, LLC [Member]
Schedule of Debt	Debt consisted of the following as of September 26, 2015 and December 27, 2014: September 26, December 27, 2015 2014 Revolving credit facility $ 60,000 $ — Long-term debt: 10 1/2% Senior Notes, due 2020: $153.8 million senior notes, including a $5.5 million net premium at September 26, 2015 and $625.0 million senior notes, including a $26.5 million net premium at December 27, 2014 159,365 651,548 6 1/8% Senior Notes, due 2023: $350.0 million senior notes, issued at par at September 26, 2015 350,000 Term Loan, due 2022: $650.0 million term loan, net of $3.1 million discount at September 26, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014 646,828 413,369 Total 1,156,193 1,064,917 Current portion of long-term debt 8,125 5,275 Long-term debt $ 1,148,068 $ 1,059,642
Schedule of Contractual Payments of Long-Term Debt	The contractual payments of long-term debt, including current maturities, for the five years subsequent to September 26, 2015, are as follows: 2015 (three months) $ 3,250 2016 6,500 2017 6,500 2018 4,875 2019 6,500 2020 161,925 Thereafter 964,250 Total 1,153,800 Plus: Original issue net premium 2,393 Total debt $ 1,156,193
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the nine months ended September 26, 2015 and September 27, 2014: Deferred financing fees Balance — December 27, 2014 $ 17,215 Loan origination fees 10,911 Amortization (2,731 ) Write off of deferred financing fees (12,135 ) Balance — September 26, 2015 $ 13,260 Balance — December 28, 2013 $ 11,485 Loan origination fees 9,281 Amortization (2,875 ) Balance —September 27, 2014 $ 17,891

Accumulated Other Comprehensi32

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 26, 2015
Accumulated Other Comprehensive Loss	The changes in each component of accumulated other comprehensive loss consisted of the following: Foreign currency Cash flow hedge Accumulated Balance — December 27, 2014 $ — $ — $ — Foreign currency translation adjustment (2,109 ) — (2,109 ) Loss on cash flow hedges — (498 ) (498 ) Balance — September 26, 2015 $ (2,109 ) $ (498 ) $ (2,607 )
Summit Materials, LLC [Member]
Accumulated Other Comprehensive Loss	The changes in each component of accumulated other comprehensive loss consisted of the following: Change in Foreign currency Cash flow hedge Accumulated Balance — December 27, 2014 $ (9,730 ) $ (5,816 ) $ — $ (15,546 ) Foreign currency translation adjustment — (11,531 ) — (11,531 ) Loss on cash flow hedges — — (1,010 ) (1,010 ) Balance — September 26, 2015 $ (9,730 ) $ (17,347 ) $ (1,010 ) $ (28,087 ) Balance — December 28, 2013 $ (6,045 ) $ — $ — $ (6,045 ) Postretirement curtailment adjustment (942 ) — — (942 ) Postretirement liability adjustment 1,515 — — 1,515 Foreign currency translation adjustment — (1,764 ) — (1,764 ) Balance —September 27, 2014 $ (5,472 ) $ (1,764 ) $ — $ (7,236 )

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Schedule of Basic to Diluted Loss Per Share	The following table reconciles basic to diluted loss per share: September 26, 2015 Three months ended Nine months ended Net income attributable to Summit Inc. $ 14,711 $ 4,355 Weighted-average common shares: Weighted average shares of Class A shares 37,920,452 31,768,406 Basic earnings per share $ 0.39 $ 0.14 Weighted average shares of Class A shares 37,920,452 31,768,406 Warrants 43,478 42,909 Weighted average dilutive shares 37,963,930 31,811,315 Diluted earnings per share $ 0.39 $ 0.14

Supplemental Cash Flow Inform34

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 26, 2015
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information is as follows: Nine months ended September 26, September 27, Cash payments: Interest $ 75,990 $ 59,179 Income taxes 1,516 1,345 Non cash financing activities: Purchase of noncontrolling interest in Continental Cement $ (29,102 ) $ —
Summit Materials, LLC [Member]
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information is as follows: Nine months ended September 26, September 27, 2015 2014 Cash payments: Interest $ 75,990 $ 59,179 Income taxes 1,516 1,345 Non cash financing activities: Purchase of noncontrolling interest in Continental Cement $ (64,102 ) $ —

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 26, 2015
Summary of Financial Data for Company's Reportable Business Segments	The following tables display selected financial data for the Company’s reportable segments: Three months ended Nine months ended September 26, September 27, September 26, September 27, Revenue: West region $ 261,742 $ 211,302 $ 597,484 $ 478,432 Central region 164,084 126,882 338,613 283,541 East region 46,079 56,575 94,738 108,172 Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 Three months ended Nine months ended September 26, September 27, September 26, September 27, Adjusted EBITDA West region $ 59,574 $ 39,105 $ 110,940 $ 71,646 Central region 53,756 30,820 89,984 59,220 East region 13,383 11,868 15,096 10,462 Corporate and other (8,879 ) (9,381 ) (33,577 ) (28,427 ) Total reportable segments and corporate 117,834 72,412 182,443 112,901 Interest expense 20,727 22,085 62,231 62,555 Depreciation, depletion, amortization and accretion 33,306 23,255 86,818 63,950 Initial public offering costs — — 28,296 — Loss on debt financings 32,641 — 64,313 — Income (loss) from continuing operations before taxes $ 31,160 $ 27,072 $ (59,215 ) $ (13,604 ) Nine months ended September 26, September 27, Cash paid for capital expenditures: West region $ 32,192 $ 25,496 Central region 24,335 28,485 East region 9,401 6,590 Total reportable segments 65,928 60,571 Corporate and other 3,744 3,673 Total capital expenditures $ 69,672 $ 64,244 Three months ended Nine months ended September 26, September 27, September 26, September 27, Depreciation, depletion, amortization and accretion: West region $ 13,786 $ 9,155 $ 38,508 $ 23,569 Central region 15,778 9,710 37,198 28,061 East region 3,114 3,984 9,426 11,272 Total reportable segments 32,678 22,849 85,132 62,902 Corporate and other 628 406 1,686 1,048 Total depreciation, depletion, amortization and accretion $ 33,306 $ 23,255 $ 86,818 $ 63,950 September 26, December 27, Total assets: West region $ 866,516 $ 777,981 Central region 1,189,565 704,134 East region 224,720 221,598 Total reportable segments 2,280,801 1,703,713 Corporate and other 49,440 26,064 Total $ 2,330,241 $ 1,729,777 Three months ended Nine months ended September 26, September 27, September 26, September 27, Revenue by product:* Aggregates $ 86,070 $ 68,636 $ 218,336 $ 160,002 Cement 68,481 34,171 110,477 69,435 Ready-mixed concrete 95,481 75,429 254,878 189,198 Asphalt 113,249 104,862 219,492 203,944 Paving and related services 185,092 191,157 366,321 391,925 Other (76,468 ) (79,496 ) (138,669 ) (144,359 ) Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 * Revenue by product includes intercompany and intracompany sales transferred at market value. The elimination of intracompany transactions is included in Other. Revenue from the liquid asphalt terminals is included in asphalt revenue.
Summit Materials, LLC [Member]
Summary of Financial Data for Company's Reportable Business Segments	The following tables display selected financial data for the Company’s reportable segments: Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Revenue: West region $ 261,742 $ 211,302 $ 597,484 $ 478,432 Central region 164,084 126,882 338,613 283,541 East region 46,079 56,575 94,738 108,172 Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Adjusted EBITDA West region $ 59,574 $ 39,105 $ 110,940 $ 71,646 Central region 53,756 30,820 89,984 59,220 East region 13,383 11,868 15,096 10,462 Corporate and other (8,879 ) (9,381 ) (33,577 ) (28,427 ) Total reportable segments and corporate 117,834 72,412 182,443 112,901 Interest expense 20,436 22,085 61,649 62,555 Depreciation, depletion, amortization and accretion 33,306 23,255 86,818 63,950 Initial public offering costs — — 28,296 — Loss on debt financings 32,641 — 64,313 — Income (loss) from continuing operations before taxes $ 31,451 $ 27,072 $ (58,633 ) $ (13,604 ) Nine months ended September 26, September 27, 2015 2014 Cash paid for capital expenditures: West region $ 32,192 $ 25,496 Central region 24,335 28,485 East region 9,401 6,590 Total reportable segments 65,928 60,571 Corporate and other 3,744 3,673 Total capital expenditures $ 69,672 $ 64,244 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Depreciation, depletion, amortization and accretion: West region $ 13,786 $ 9,155 $ 38,508 $ 23,569 Central region 15,778 9,710 37,198 28,061 East region 3,114 3,984 9,426 11,272 Total reportable segments 32,678 22,849 85,132 62,902 Corporate and other 628 406 1,686 1,048 Total depreciation, depletion, amortization and accretion $ 33,306 $ 23,255 $ 86,818 $ 63,950 September 26, December 27, 2015 2014 Total assets: West region $ 866,516 $ 777,981 Central region 1,189,565 704,134 East region 224,720 221,598 Total reportable segments 2,280,801 1,703,713 Corporate and other 35,935 26,064 Total $ 2,316,736 $ 1,729,777 Three months ended Nine months ended September 26, September 27, September 26, September 27, 2015 2014 2015 2014 Revenue by product:* Aggregates $ 86,070 $ 68,636 $ 218,336 $ 160,002 Cement 68,481 34,171 110,477 69,435 Ready-mixed concrete 95,481 75,429 254,878 189,198 Asphalt 113,249 104,862 219,492 203,944 Paving and related services 185,092 191,157 366,321 391,925 Other (76,468 ) (79,496 ) (138,669 ) (144,359 ) Total revenue $ 471,905 $ 394,759 $ 1,030,835 $ 870,145 * Revenue by product includes intercompany and intracompany sales transferred at market value. The elimination of intracompany transactions is included in Other. Revenue from the liquid asphalt terminals is included in asphalt revenue.

Guarantor and Non-Guarantor F36

Guarantor and Non-Guarantor Financial Information (Tables) - Summit Materials, LLC [Member]	9 Months Ended
	Sep. 26, 2015
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 8,989 $ 1,025 $ 8,130 $ (12,662 ) $ 5,482 Accounts receivable, net — 195,120 11,163 (344 ) 205,939 Intercompany receivables 1,322,050 14,869 8,996 (1,345,915 ) — Cost and estimated earnings in excess of billings — 33,447 728 — 34,175 Inventories — 132,734 5,302 — 138,036 Other current assets 1,088 19,319 1,355 — 21,762 Total current assets 1,332,127 396,514 35,674 (1,358,921 ) 405,394 Property, plant and equipment, net 9,433 1,240,126 26,668 — 1,276,227 Goodwill — 519,759 48,077 — 567,836 Intangible assets, net — 14,044 1,437 — 15,481 Other assets 881,923 132,532 1,271 (963,928 ) 51,798 Total assets $ 2,223,483 $ 2,302,975 $ 113,127 $ (2,322,849 ) $ 2,316,736 Liabilities, Redeemable Noncontrolling Interest and Member’s Interest Current liabilities: Current portion of debt $ 68,125 $ — $ — $ — $ 68,125 Current portion of acquisition-related liabilities — 17,691 — — 17,691 Accounts payable 7,436 102,571 3,563 (344 ) 113,226 Accrued expenses 30,998 70,386 2,158 (12,662 ) 90,880 Intercompany payables 67,671 1,274,510 3,734 (1,345,915 ) — Billings in excess of costs and estimated earnings — 10,983 22 — 11,005 Total current liabilities 174,230 1,476,141 9,477 (1,358,921 ) 300,927 Long-term debt 1,148,068 61,377 — (61,377 ) 1,148,068 Acquisition-related liabilities — 33,320 — — 33,320 Other noncurrent liabilities 1,558 110,856 57,268 (55,107 ) 114,575 Total liabilities 1,323,856 1,681,694 66,745 (1,475,405 ) 1,596,890 Redeemable noncontrolling interest — — — — — Redeemable members’ interest — — — — — Total stockholders’ equity/partners’ interest 899,627 621,281 46,382 (847,444 ) 719,846 Total liabilities, redeemable noncontrolling interest and member’s interest $ 2,223,483 $ 2,302,975 $ 113,127 $ (2,322,849 ) $ 2,316,736 Condensed Consolidating Balance Sheets December 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- inations Consol- idated Assets Current assets: Cash and cash equivalents $ 10,837 $ 2 $ 695 $ 8,793 $ (7,112 ) $ 13,215 Accounts receivable, net 1 6,629 124,380 11,525 (1,233 ) 141,302 Intercompany receivables 376,344 4,095 30,539 4,052 (415,030 ) — Cost and estimated earnings in excess of billings — — 9,819 355 — 10,174 Inventories — 8,696 98,188 4,669 — 111,553 Other current assets 7,148 464 9,638 1,775 (1,853 ) 17,172 Total current assets 394,330 19,886 273,259 31,169 (425,228 ) 293,416 Property, plant and equipment, net 7,035 302,524 610,717 30,325 — 950,601 Goodwill — 23,124 340,969 55,177 — 419,270 Intangible assets, net — 542 14,245 2,860 — 17,647 Other assets 1,153,204 25,233 125,462 1,362 (1,256,418 ) 48,843 Total assets $ 1,554,569 $ 371,309 $ 1,364,652 $ 120,893 $ (1,681,646 ) $ 1,729,777 Liabilities, Redeemable Noncontrolling Interest and Member’s Interest Current liabilities: Current portion of debt $ 5,275 $ 1,273 $ 3,990 $ — $ (5,263 ) $ 5,275 Current portion of acquisition-related liabilities 166 — 18,236 — — 18,402 Accounts payable 3,655 6,845 65,018 4,569 (1,233 ) 78,854 Accrued expenses 37,101 10,178 59,477 3,705 (8,965 ) 101,496 Intercompany payables 162,728 4,052 245,416 2,834 (415,030 ) — Billings in excess of costs and estimated earnings — — 8,931 27 — 8,958 Total current liabilities 208,925 22,348 401,068 11,135 (430,491 ) 212,985 Long-term debt 1,059,642 153,318 480,599 — (633,917 ) 1,059,642 Acquisition-related liabilities — — 42,736 — — 42,736 Other noncurrent liabilities 796 24,787 65,479 57,736 (55,107 ) 93,691 Total liabilities 1,269,363 200,453 989,882 68,871 (1,119,515 ) 1,409,054 Redeemable noncontrolling interest — — — — 33,740 33,740 Redeemable members’ interest — 34,543 — — (34,543 ) — Total stockholders’ equity/partners’ interest 285,206 136,313 374,770 52,022 (561,328 ) 286,983 Total liabilities, redeemable noncontrolling interest and member’s interest $ 1,554,569 $ 371,309 $ 1,364,652 $ 120,893 $ (1,681,646 ) $ 1,729,777
Condensed Consolidating Statements of Operations	Condensed Consolidating Statements of Operations For the three months ended September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Revenue $ — $ 454,501 $ 21,472 $ (4,068 ) $ 471,905 Cost of revenue (excluding items shown separately below) — 304,204 12,263 (4,068 ) 312,399 General and administrative expenses 8,881 32,362 1,600 — 42,843 Depreciation, depletion, amortization and accretion 628 31,374 1,304 — 33,306 Operating (loss) income (9,509 ) 86,561 6,305 — 83,357 Other (income) expense, net (58,666 ) 3,639 (17 ) 86,514 31,470 Interest expense 15,046 15,286 900 (10,796 ) 20,436 Income from continuing operations before taxes 34,111 67,636 5,422 (75,718 ) 31,451 Income tax benefit (expense) — (2,690 ) 35 — (2,655 ) Income from continuing operations 34,111 70,326 5,387 (75,718 ) 34,106 Income from discontinued operations — (57 ) — — (57 ) Net income 34,111 70,383 5,387 (75,718 ) 34,163 Net income attributable to minority interest — — — 52 52 Net income attributable to member of Summit Materials, LLC $ 34,111 $ 70,383 $ 5,387 $ (75,770 ) $ 34,111 Comprehensive income attributable to member of Summit Materials, LLC $ 26,805 $ 69,373 $ (909 ) $ (68,464 ) $ 26,805 Condensed Consolidating Statements of Operations For the three months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Revenue $ — $ 34,171 $ 348,785 $ 22,626 $ (10,823 ) $ 394,759 Cost of revenue (excluding items shown separately below) — 25,603 253,284 17,433 (10,823 ) 285,497 General and administrative expenses 8,694 1,651 27,418 495 — 38,258 Depreciation, depletion, amortization and accretion 406 3,708 18,618 523 — 23,255 Operating (loss) income (9,100 ) 3,209 49,465 4,175 — 47,749 Other (income) expense, net (43,887 ) (945 ) (2,679 ) (16 ) 46,119 (1,408 ) Interest expense 7,913 2,931 13,416 233 (2,408 ) 22,085 Income from continuing operations before taxes 26,874 1,223 38,728 3,958 (43,711 ) 27,072 Income tax benefit (expense) — — (1,038 ) — — (1,038 ) Income from continuing operations 26,874 1,223 39,766 3,958 (43,711 ) 28,110 Income from discontinued operations — — (7 ) — — (7 ) Net income 26,874 1,223 39,773 3,958 (43,711 ) 28,117 Net income attributable to minority interest — — — — 1,243 1,243 Net income attributable to member of Summit Materials, LLC $ 26,874 $ 1,223 $ 39,773 $ 3,958 $ (44,954 ) $ 26,874 Comprehensive income attributable to member of Summit Materials, LLC $ 25,110 $ 1,223 $ 39,773 $ 2,194 $ (43,190 ) $ 25,110 Condensed Consolidating Statements of Operations For the nine months ended September 26, 2015 Issuers Wholly- Non- Eliminations Consolidated Revenue $ — $ 980,153 $ 78,821 $ (28,139 ) $ 1,030,835 Cost of revenue (excluding items shown separately below) — 696,068 51,909 (28,139 ) 719,838 General and administrative expenses 61,634 90,959 4,935 — 157,528 Depreciation, depletion, amortization and accretion 1,686 80,997 4,135 — 86,818 Operating (loss) income (63,320 ) 112,129 17,842 — 66,651 Other (income) expense, net (55,083 ) 7,140 142 111,436 63,635 Interest expense 35,196 45,332 2,689 (21,568 ) 61,649 Income from continuing operations before taxes (43,433 ) 59,657 15,011 (89,868 ) (58,633 ) Income tax benefit (expense) — (12,852 ) 384 — (12,468 ) Income from continuing operations (43,433 ) 72,509 14,627 (89,868 ) (46,165 ) Income from discontinued operations — (815 ) — — (815 ) Net income (43,433 ) 73,324 14,627 (89,868 ) (45,350 ) Net income attributable to minority interest — — — (1,917 ) (1,917 ) Net income attributable to member of Summit Materials, LLC $ (43,433 ) $ 73,324 $ 14,627 $ (87,951 ) $ (43,433 ) Comprehensive income attributable to member of Summit Materials, LLC $ (55,974 ) $ 72,314 $ 3,096 $ (75,410 ) $ (55,974 ) Condensed Consolidating Statements of Operations For the nine months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Revenue $ — $ 69,435 $ 776,502 $ 43,900 $ (19,692 ) $ 870,145 Cost of revenue (excluding items shown separately below) — 53,229 581,602 30,795 (19,692 ) 645,934 General and administrative expenses 26,384 5,225 80,938 1,062 — 113,609 Depreciation, depletion, amortization and accretion 1,047 10,484 51,351 1,068 — 63,950 Operating (loss) income (27,431 ) 497 62,611 10,975 — 46,652 Other expense (income), net (36,161 ) (2,303 ) (4,233 ) 29 40,369 (2,299 ) Interest expense 21,581 8,788 37,831 289 (5,934 ) 62,555 (Loss) income from continuing operations before taxes (12,851 ) (5,988 ) 29,013 10,657 (34,435 ) (13,604 ) Income tax benefit (1,427 ) — (1,071 ) — — (2,498 ) (Loss) income from continuing operations (11,424 ) (5,988 ) 30,084 10,657 (34,435 ) (11,106 ) Income from discontinued operations — — (356 ) — — (356 ) Net (loss) income (11,424 ) (5,988 ) 30,440 10,657 (34,435 ) (10,750 ) Net loss attributable to noncontrolling interest — — — — 674 674 Net (loss) income attributable to member of Summit Materials, LLC $ (11,424 ) $ (5,988 ) $ 30,440 $ 10,657 $ (35,109 ) $ (11,424 ) Comprehensive (loss) income attributable to member of Summit Materials, LLC $ (12,615 ) (5,170 ) $ 30,440 $ 8,893 $ (34,163 ) $ (12,615 )
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows For the nine months ended September 26, 2015 Issuers Wholly- Non- Elim- Consol- Net cash (used in) provided by operating activities $ (140,504 ) $ 112,541 $ 9,203 $ (167 ) $ (18,927 ) Cash flow from investing activities: Acquisitions, net of cash acquired — (505,466 ) — — (505,466 ) Purchase of property, plant and equipment (3,743 ) (65,001 ) (928 ) — (69,672 ) Proceeds from the sale of property, plant, and equipment — 8,821 62 — 8,883 Other — 610 — — 610 Net cash used for investing activities (3,743 ) (561,036 ) (866 ) — (565,645 ) Cash flow from financing activities: Proceeds from investment by member 490,916 — — — 490,916 Capital issuance costs (12,539 ) — — — (12,539 ) Net proceeds from debt issuance 1,415,750 — — — 1,415,750 Loans received from and payments made on loans from other Summit Companies (1,031,576 ) 1,047,015 (9,000 ) (6,439 ) — Payments on long-term debt (669,123 ) (583,340 ) — 1,056 (1,251,407 ) Payments on acquisition-related liabilities (166 ) (14,852 ) — — (15,018 ) Financing costs (10,911 ) — — — (10,911 ) Distributions from partnership (39,952 ) — — — (39,952 ) Other — — — — — Net cash provided by (used for) financing activities 142,399 448,823 (9,000 ) (5,383 ) 576,839 Net increase (decrease) in cash (1,848 ) 328 (663 ) (5,550 ) (7,733 ) Cash — Beginning of period 10,837 697 8,793 (7,112 ) 13,215 Cash— End of period $ 8,989 $ 1,025 $ 8,130 $ (12,662 ) $ 5,482 Condensed Consolidating Statements of Cash Flows For the nine months ended September 27, 2014 Issuers Non- Wholly- Wholly- Non- Elim- Consol- Net cash used in operating activities $ (36,504 ) $ (2,408 ) $ 28,727 $ 668 $ (1,319 ) $ (10,836 ) Cash flow from investing activities: Acquisitions, net of cash acquired (181,754 ) — (170,187 ) — — (351,941 ) Purchase of property, plant and equipment (3,674 ) (13,472 ) (46,575 ) (523 ) — (64,244 ) Proceeds from the sale of property, plant, and equipment — — 9,345 230 — 9,575 Other — — (409 ) — 1,166 757 Net cash (used for) provided by investing activities (185,428 ) (13,472 ) (207,826 ) (293 ) 1,166 (405,853 ) Cash flow from financing activities: Proceeds from investment by member 24,350 — — 1,353 (1,353 ) 24,350 Net proceeds from debt issuance 657,217 — — — — 657,217 Loans received from and payments made on loans from other Summit Companies (195,590 ) 16,383 189,243 (2,113 ) (7,923 ) — Payments on long-term debt (251,062 ) (509 ) (6,766 ) — — (258,337 ) Payments on acquisition-related liabilities (1,500 ) — (4,307 ) — — (5,807 ) Financing costs (8,834 ) — — — — (8,834 ) Other (88 ) — (1,500 ) — 1,500 (88 ) Net cash provided by (used for) financing activities 224,493 15,874 176,670 (760 ) (7,776 ) 408,501 Net increase (decrease) in cash 2,561 (6 ) (2,429 ) (385 ) (7,929 ) (8,188 ) Cash — Beginning of period 10,375 9 3,442 3,631 (2,540 ) 14,917 Cash— End of period $ 12,936 $ 3 $ 1,013 $ 3,246 $ (10,469 ) $ 6,729

Summary of Organization and S37

Summary of Organization and Significant Accounting Policies - Additional Information (Detail)	Aug. 11, 2015USD ($)$ / sharesshares	Sep. 26, 2015USD ($)$ / sharesshares	Sep. 26, 2015USD ($)Customer$ / sharesshares	Sep. 27, 2014USD ($)Customer	Aug. 11, 2015USD ($)$ / shares	Sep. 26, 2015USD ($)CustomerSegmentState$ / sharesshares	Sep. 27, 2014USD ($)Customer	Dec. 27, 2014USD ($)
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments | Segment						3
Date of incorporation						Sep. 23, 2014
Number of customers accounted for more than 10% of total revenue | Customer			0	0		0	0
Number of operating states | State						18
Reductions recognized in contingent consideration			$ 0	$ 0		$ 0	$ 0
Interest rate derivatives		$ 200,000,000	$ 200,000,000			200,000,000
Aggregate consideration for acquiring noncontrolling interests						497,848,000
Cash consideration						35,000,000
Aggregate principal amount of non-interest bearing notes payable						15,000,000
Annual installments amount of non-interest bearing notes payable						2,500,000
Decrease in other assets (noncurrent)						$ 524,000	$ 675,000
Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments | Segment						3
Date of incorporation						Sep. 23, 2014
Number of customers accounted for more than 10% of total revenue | Customer			0	0		0	0
Number of operating states | State						18
Reductions recognized in contingent consideration			$ 0	$ 0		$ 0	$ 0
Interest rate derivatives		$ 200,000,000	$ 200,000,000			200,000,000
Aggregate consideration for acquiring noncontrolling interests						64,100,000
Aggregate principal amount of non-interest bearing notes payable						15,000,000
Annual installments amount of non-interest bearing notes payable						2,500,000
Decrease in other assets (noncurrent)						524,000	$ 675,000
Cash consideration						35,000,000
Accounting Standards Update (ASU) 2015-03 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Decrease in other assets (noncurrent)						8,800,000
Decrease in long-term debt								$ 16,800,000
Accounting Standards Update (ASU) 2015-03 [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Decrease in other assets (noncurrent)						$ (8,800,000)
Decrease in long-term debt								$ (16,800,000)
Level 3 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Discount rate						11.00%
Level 3 [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Discount rate						11.00%
Variable Interest Entity, Primary Beneficiary [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Percentage of voting power						100.00%
Noncontrolling interest elimination percentage		50.70%			72.20%
Continental Cement Company, L.L.C. [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage		30.00%	30.00%			30.00%
Continental Cement Company, L.L.C. [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage		30.00%	30.00%			30.00%
Ohio Valley Asphalt, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage		20.00%	20.00%			20.00%
Ohio Valley Asphalt, LLC [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage		20.00%	20.00%			20.00%
Common Class A [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares						1,029,183
Common Class A [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares						1,029,183
10 1/2% Senior Notes, due 2020 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, interest rate		10.50%	10.50%			10.50%		10.50%
Debt instrument, face amount		$ 153,800,000	$ 153,800,000			$ 153,800,000		$ 625,000,000
10 1/2% Senior Notes, due 2020 [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, interest rate		10.50%	10.50%			10.50%		10.50%
Debt instrument, face amount		$ 153,800,000	$ 153,800,000			$ 153,800,000		$ 625,000,000
Initial Public Offering [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Operations commenced date						Mar. 11, 2015
Net proceeds from IPO						$ 433,000,000
Initial Public Offering [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Operations commenced date						Mar. 11, 2015
Net proceeds from IPO						$ 433,000,000
Initial Public Offering [Member] | Blackstone Management Partners L.L.C. [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Payment of termination fee to affiliates of Sponsors						13,800,000
Initial Public Offering [Member] | Blackstone Management Partners L.L.C. [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Payment of termination fee to affiliates of Sponsors						$ 13,800,000
Initial Public Offering [Member] | Common Class A [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares						25,555,555
Class A Common stock offering price per share | $ / shares		$ 18	$ 18			$ 18
Initial Public Offering [Member] | Common Class A [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares						25,555,555
Class A Common stock offering price per share | $ / shares		$ 18	$ 18			$ 18
Initial Public Offering [Member] | 10 1/2% Senior Notes, due 2020 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, aggregate principal amount redeemed		$ 288,200,000	$ 288,200,000			$ 288,200,000
Senior notes, interest rate		10.50%	10.50%			10.50%
Senior notes, redemption date						Jan. 31, 2020
Debt instrument, face amount		$ 288,200,000	$ 288,200,000			$ 288,200,000
Debt Instrument, redemption premium						38,200,000
Accrued and unpaid interest		5,200,000	5,200,000			5,200,000
Initial Public Offering [Member] | 10 1/2% Senior Notes, due 2020 [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, aggregate principal amount redeemed		$ 288,200,000	$ 288,200,000			$ 288,200,000
Senior notes, interest rate		10.50%	10.50%			10.50%
Senior notes, redemption date						Jan. 31, 2020
Debt instrument, face amount		$ 288,200,000	$ 288,200,000			$ 288,200,000
Debt Instrument, redemption premium						38,200,000
Accrued and unpaid interest		$ 5,200,000	$ 5,200,000			$ 5,200,000
Follow on Public Offering [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares	22,425,000
Class A Common stock offering price per share | $ / shares	$ 25.75				$ 25.75
Net proceeds from IPO	$ 555,800,000
Number of newly-issued shares purchased from Summit Holdings | shares	3,750,000
Number of shares purchased from outstanding shares of Summit Holding | shares	18,675,000
Amount of purchase price due	$ 80,000,000				$ 80,000,000
Follow on Public Offering [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares | shares	22,425,000
Class A Common stock offering price per share | $ / shares	$ 25.75				$ 25.75
Net proceeds from IPO	$ 555,800,000
Number of newly-issued shares purchased from Summit Holdings | shares	3,750,000
Number of shares purchased from outstanding shares of Summit Holding | shares	18,675,000
Amount of purchase price due	$ 80,000,000				$ 80,000,000
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Customer accounted revenue			10.00%	10.00%		10.00%	10.00%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Customer accounted revenue			10.00%	10.00%		10.00%	10.00%
Class B Units [Member] | Initial Public Offering [Member] | Continental Cement Company, L.L.C. [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class B capital units purchased | shares		71,428,571	71,428,571			71,428,571
Class B Units [Member] | Initial Public Offering [Member] | Continental Cement Company, L.L.C. [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class B capital units purchased | shares		71,428,571	71,428,571			71,428,571

Summary of Organization and S38

Summary of Organization and Significant Accounting Policies - Schedule of Contingent Consideration Obligations Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	$ 4,559	$ 2,375
Cash flow hedge	114
Contingent consideration	2,711	5,379
Cash flow hedge	897
Summit Materials, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	4,559	2,375
Cash flow hedge	114
Contingent consideration	2,711	$ 5,379
Cash flow hedge	$ 897

Summary of Organization and S39

Summary of Organization and Significant Accounting Policies - Schedule of Carrying Value and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Debt Instrument [Line Items]
Long-term debt, Carrying Value	$ 1,156,193	$ 1,064,917
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, Carrying Value	1,156,193	1,064,917
Level 2 [Member]
Debt Instrument [Line Items]
Long-term debt, Fair Value	1,155,557	1,101,873
Long-term debt, Carrying Value	1,156,193	1,064,917
Level 2 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, Fair Value	1,155,557	1,101,873
Long-term debt, Carrying Value	1,156,193	1,064,917
Level 3 [Member]
Debt Instrument [Line Items]
Current portion of deferred consideration and noncompete obligations, Fair Value	15,632	16,027
Long term portion of deferred consideration and noncompete obligations, Fair Value	39,267	37,357
Current portion of deferred consideration and noncompete obligations, Carrying Value	15,632	16,027
Long term portion of deferred consideration and noncompete obligations, Carrying Value	39,267	37,357
Level 3 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Current portion of deferred consideration and noncompete obligations, Fair Value	13,132	16,027
Long term portion of deferred consideration and noncompete obligations, Fair Value	30,609	37,357
Current portion of deferred consideration and noncompete obligations, Carrying Value	13,132	16,027
Long term portion of deferred consideration and noncompete obligations, Carrying Value	$ 30,609	$ 37,357

Summary of Organization and S40

Summary of Organization and Significant Accounting Policies - Schedule of Carrying Value and Fair Value of Financial Instruments (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Debt Instrument [Line Items]
Current portion of debt	$ 8,100	$ 5,300
Remaining borrowing capacity	60,000
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Current portion of debt	8,100	$ 5,300
Remaining borrowing capacity	60,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Remaining borrowing capacity	60,000
Revolving Credit Facility [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Remaining borrowing capacity	$ 60,000

Reorganization - Additional Inf

Reorganization - Additional Information (Detail) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 26, 2015USD ($)$ / sharesshares
Reorganization Items [Line Items]
Number of LP Units outstanding	69,007,297
Vesting period of leverage restoration options	4 years
Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Number of LP Units outstanding	69,007,297
Vesting period of leverage restoration options	4 years
General and Administrative Expense Costs [Member]
Reorganization Items [Line Items]
Modification charge recognized in general and administrative costs | $	$ 14.5
General and Administrative Expense Costs [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Modification charge recognized in general and administrative costs | $	$ 14.5
Common Class A-2 [Member]
Reorganization Items [Line Items]
Number of LP Units outstanding	0
Common Class A [Member]
Reorganization Items [Line Items]
Class A common shares	1,029,183
Common Class A [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Class A common shares	1,029,183
Common Class A [Member] | 2015 Omnibus Equity Incentive Plan [Member]
Reorganization Items [Line Items]
Number of class A common stock issued under the Omnibus Incentive Plan	240,000
Exercise price per share under the Omnibus Incentive Plan | $ / shares	$ 18
Common Class A [Member] | 2015 Omnibus Equity Incentive Plan [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Number of class A common stock issued under the Omnibus Incentive Plan	240,000
Exercise price per share under the Omnibus Incentive Plan | $ / shares	$ 18
Share-based Compensation Award, Tranche One [Member] | 2015 Omnibus Equity Incentive Plan [Member]
Reorganization Items [Line Items]
Percentage of performance-vesting options	25.00%
Share-based Compensation Award, Tranche One [Member] | 2015 Omnibus Equity Incentive Plan [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Percentage of performance-vesting options	25.00%
Initial Public Offering [Member] | Common Class A [Member]
Reorganization Items [Line Items]
Class A common shares	25,555,555
Class A Common stock offering price per share | $ / shares	$ 18
Initial Public Offering [Member] | Common Class A [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Class A common shares	25,555,555
Class A Common stock offering price per share | $ / shares	$ 18
Class C Units [Member] | Common Class A [Member]
Reorganization Items [Line Items]
Class A common shares	160,333
Class C Units [Member] | Common Class A [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Class A common shares	160,333
Class D Units [Member] | Common Class A [Member]
Reorganization Items [Line Items]
Class A common shares	4,358,842
Class D Units [Member] | Common Class A [Member] | Summit Materials, LLC [Member]
Reorganization Items [Line Items]
Class A common shares	4,358,842

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - Davenport Acquisition [Member] - USD ($) $ in Thousands	Sep. 26, 2015	Jul. 17, 2015	Sep. 26, 2015
Business Acquisition [Line Items]
Net cash paid for acquisitions	$ 448,710	$ 448,710
Pro forma adjustment, reduction of transaction costs			$ 4,500
Pro forma adjustment, additional depreciation, depletion, amortization and accretion			7,500
Summit Materials, LLC [Member]
Business Acquisition [Line Items]
Net cash paid for acquisitions	$ 448,710	$ 448,710
Pro forma adjustment, reduction of transaction costs			4,500
Pro forma adjustment, additional depreciation, depletion, amortization and accretion			$ 7,500

Acquisitions - Summary of Profo

Acquisitions - Summary of Proforma Information (Detail) - Davenport Acquisition [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015
Business Acquisition [Line Items]
Revenue	$ 477,706	$ 1,069,305
Net income	27,649	26,764
Summit Materials, LLC [Member]
Business Acquisition [Line Items]
Revenue	477,706	1,069,305
Net income	$ 67,229	$ 24,506

Acquisitions - Summary of Asset

Acquisitions - Summary of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Jul. 17, 2015	Dec. 27, 2014
Business Acquisition [Line Items]
Goodwill	$ 567,836		$ 419,270
Summit Materials, LLC [Member]
Business Acquisition [Line Items]
Goodwill	567,836		$ 419,270
Davenport Acquisition [Member]
Business Acquisition [Line Items]
Inventories	21,538
Property, plant and equipment	272,815
Other assets	6,537
Financial liabilities	(1,509)
Other long-term liabilities	(95)
Net assets acquired	299,286
Goodwill	150,710
Total consideration	449,996
Transfer of assets	(2,182)
Working capital true-up	896
Net cash paid for acquisitions	448,710	$ 448,710
Davenport Acquisition [Member] | Summit Materials, LLC [Member]
Business Acquisition [Line Items]
Inventories	21,538
Property, plant and equipment	272,815
Other assets	6,537
Financial liabilities	(1,509)
Other long-term liabilities	(95)
Net assets acquired	299,286
Goodwill	150,710
Total consideration	449,996
Transfer of assets	(2,182)
Working capital true-up	896
Net cash paid for acquisitions	$ 448,710	$ 448,710

Goodwill - Summary of Changes i

Goodwill - Summary of Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 26, 2015USD ($)
Goodwill [Line Items]
Beginning balance	$ 419,270
Acquisitions	155,508
Foreign currency translation adjustments	(6,942)
Ending balance	567,836
Summit Materials, LLC [Member]
Goodwill [Line Items]
Beginning balance	419,270
Acquisitions	155,508
Foreign currency translation adjustments	(6,942)
Ending balance	567,836
West Region [Member]
Goodwill [Line Items]
Beginning balance	297,085
Acquisitions	4,579
Foreign currency translation adjustments	(6,942)
Ending balance	294,722
West Region [Member] | Summit Materials, LLC [Member]
Goodwill [Line Items]
Beginning balance	297,085
Acquisitions	4,579
Foreign currency translation adjustments	(6,942)
Ending balance	294,722
Central Region [Member]
Goodwill [Line Items]
Beginning balance	96,025
Acquisitions	150,929
Ending balance	246,954
Central Region [Member] | Summit Materials, LLC [Member]
Goodwill [Line Items]
Beginning balance	96,025
Acquisitions	150,929
Ending balance	246,954
East Region [Member]
Goodwill [Line Items]
Beginning balance	26,160
Ending balance	26,160
East Region [Member] | Summit Materials, LLC [Member]
Goodwill [Line Items]
Beginning balance	26,160
Ending balance	$ 26,160

Accounts Receivable, Net - Summ

Accounts Receivable, Net - Summary of Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 194,235	$ 131,060
Retention receivables	13,396	12,053
Receivables from related parties	705	333
Accounts receivable	208,336	143,446
Less: Allowance for doubtful accounts	(2,397)	(2,144)
Accounts receivable, net	205,939	141,302
Summit Materials, LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	194,235	131,060
Retention receivables	13,396	12,053
Receivables from related parties	705	333
Accounts receivable	208,336	143,446
Less: Allowance for doubtful accounts	(2,397)	(2,144)
Accounts receivable, net	$ 205,939	$ 141,302

Inventories - Components of Inv

Inventories - Components of Inventories (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Inventory [Line Items]
Aggregate stockpiles	$ 90,776	$ 88,211
Finished goods	11,284	8,826
Work in process	6,511	1,801
Raw materials	29,465	12,715
Total	138,036	111,553
Summit Materials, LLC [Member]
Inventory [Line Items]
Aggregate stockpiles	90,776	88,211
Finished goods	11,284	8,826
Work in process	6,511	1,801
Raw materials	29,465	12,715
Total	$ 138,036	$ 111,553

Accrued Expenses - Components o

Accrued Expenses - Components of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Schedule Of Accrued Expenses [Line Items]
Interest	$ 12,973	$ 32,475
Payroll and benefits	22,095	20,326
Capital lease obligations	16,065	17,530
Insurance	13,710	11,402
Non-income taxes	10,221	5,520
Professional fees	1,305	3,299
Other	14,511	10,944
Total	90,880	101,496
Summit Materials, LLC [Member]
Schedule Of Accrued Expenses [Line Items]
Interest	12,973	32,475
Payroll and benefits	22,095	20,326
Capital lease obligations	16,065	17,530
Insurance	13,710	11,402
Non-income taxes	10,221	5,520
Professional fees	1,305	3,299
Other	14,511	10,944
Total	$ 90,880	$ 101,496

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Debt Instrument [Line Items]
Revolving credit facility	$ 60,000
Long-term debt:
Long-term debt, total	1,156,193	$ 1,064,917
Long-term debt, total	1,156,193	1,064,917
Current portion of long-term debt	8,125	5,275
Long-term debt	1,148,068	1,059,642
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Revolving credit facility	60,000
Long-term debt:
Long-term debt, total	1,156,193	1,064,917
Long-term debt, total	1,156,193	1,064,917
Current portion of long-term debt	8,125	5,275
Long-term debt	1,148,068	1,059,642
10 1/2% Senior Notes, due 2020 [Member]
Long-term debt:
Long-term debt, total	159,365	651,548
Long-term debt, total	159,365	651,548
10 1/2% Senior Notes, due 2020 [Member] | Summit Materials, LLC [Member]
Long-term debt:
Long-term debt, total	159,365	651,548
Long-term debt, total	159,365	651,548
6 1/8% Senior Notes, due 2023 [Member]
Long-term debt:
Long-term debt, total	350,000
Long-term debt, total	350,000
6 1/8% Senior Notes, due 2023 [Member] | Summit Materials, LLC [Member]
Long-term debt:
Long-term debt, total	350,000
Long-term debt, total	350,000
Term Loan, due 2022 [Member] | Credit Facility [Member]
Long-term debt:
Long-term debt, total	646,828	413,369
Long-term debt, total	646,828	413,369
Term Loan, due 2022 [Member] | Summit Materials, LLC [Member] | Credit Facility [Member]
Long-term debt:
Long-term debt, total	646,828	413,369
Long-term debt, total	$ 646,828	$ 413,369

Debt - Schedule of Debt (Parent

Debt - Schedule of Debt (Parenthetical) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 26, 2015	Dec. 27, 2014
10 1/2% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt, face value	$ 153.8	$ 625
Original issuance discount	$ 5.5	$ 26.5
Debt instrument interest rate	10.50%	10.50%
Debt instrument maturity year	Dec. 1, 2020	Dec. 1, 2020
10 1/2% Senior Notes, due 2020 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, face value	$ 153.8	$ 625
Original issuance discount	$ 5.5	$ 26.5
Debt instrument interest rate	10.50%	10.50%
Debt instrument maturity year	Dec. 1, 2020	Dec. 1, 2020
6 1/8% Senior Notes, due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	6.125%
Debt instrument maturity year	Jul. 15, 2023
6 1/8% Senior Notes, due 2023 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	6.125%
Debt instrument maturity year	Jul. 15, 2023
Term Loan, due 2022 [Member] | Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, face value	$ 650	$ 415.7
Original issuance discount	$ 3.1	$ 2.3
Debt instrument maturity year	Dec. 1, 2022	Dec. 1, 2022
Term Loan, due 2022 [Member] | Credit Facility [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, face value	$ 650	$ 415.7
Original issuance discount	$ 3.1	$ 2.3
Debt instrument maturity year	Dec. 1, 2022	Dec. 1, 2022

Debt - Schedule of Contractual

Debt - Schedule of Contractual Payments of Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Long Term Debt Maturities Repayments Of Principal [Line Items]
2015 (three months)	$ 3,250
2,016	6,500
2,017	6,500
2,018	4,875
2,019	6,500
2,020	161,925
Thereafter	964,250
Total	1,153,800
Plus: Original issue net premium	2,393
Long-term debt, total	1,156,193	$ 1,064,917
Summit Materials, LLC [Member]
Long Term Debt Maturities Repayments Of Principal [Line Items]
2015 (three months)	3,250
2,016	6,500
2,017	6,500
2,018	4,875
2,019	6,500
2,020	161,925
Thereafter	964,250
Total	1,153,800
Plus: Original issue net premium	2,393
Long-term debt, total	$ 1,156,193	$ 1,064,917

Debt - Senior Notes - Additiona

Debt - Senior Notes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 26, 2015	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014	Aug. 31, 2015	Apr. 30, 2015	Sep. 08, 2014	Jan. 17, 2014
Debt Instrument [Line Items]
Proceeds from issuance of debt		$ 1,415,750,000	$ 657,217,000
Premium of debt instrument	$ 2,393,000	2,393,000
Write off of deferred financing fees		$ 12,135,000
6 1/8% Senior Notes, due 2023 [Member]
Debt Instrument [Line Items]
Senior notes, interest rate	6.125%	6.125%
Debt instrument maturity year		Jul. 15, 2023
10 1/2% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 153,800,000	$ 153,800,000		$ 625,000,000
Senior notes, interest rate	10.50%	10.50%		10.50%
Debt instrument maturity year		Dec. 1, 2020		Dec. 1, 2020
10 1/2% Senior Notes, due 2020 [Member] | Initial Public Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 288,200,000	$ 288,200,000
Senior notes, interest rate	10.50%	10.50%
Debt Instrument, redemption premium		$ 38,200,000
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Proceeds from issuance of debt		1,415,750,000	$ 657,217,000
Premium of debt instrument	$ 2,393,000	2,393,000
Write off of deferred financing fees		$ 12,135,000
Summit Materials, LLC [Member] | 6 1/8% Senior Notes, due 2023 [Member]
Debt Instrument [Line Items]
Senior notes, interest rate	6.125%	6.125%
Debt instrument maturity year		Jul. 15, 2023
Summit Materials, LLC [Member] | 10 1/2% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 153,800,000	$ 153,800,000		$ 625,000,000
Senior notes, interest rate	10.50%	10.50%		10.50%
Debt instrument maturity year		Dec. 1, 2020		Dec. 1, 2020
Summit Materials, LLC [Member] | 10 1/2% Senior Notes, due 2020 [Member] | Initial Public Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 288,200,000	$ 288,200,000
Senior notes, interest rate	10.50%	10.50%
Debt Instrument, redemption premium		$ 38,200,000
Senior Notes [Member]
Debt Instrument [Line Items]
Refinance of existing senior secured term loan facility					$ 183,000,000
Senior Notes [Member] | Davenport Acquisition [Member]
Debt Instrument [Line Items]
Initial purchase price		370,000,000
Senior Notes [Member] | 6 1/8% Senior Notes, due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 350,000,000	$ 350,000,000
Senior notes, interest rate	6.125%	6.125%
Percentage of par value of senior notes		100.00%
Debt instrument maturity year		Jul. 15, 2023
Notes payable commencing date		Jan. 15, 2016
Senior Notes [Member] | 10 1/2% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, amount redeemed		$ 183,000,000
Charges on redemption	$ 14,100,000	45,400,000
Debt Instrument, redemption premium	18,200,000	56,400,000
Write off of deferred financing fees	2,800,000	7,500,000
Net benefit from the write-off the original issuance premium and discount	6,900,000	18,500,000
Senior Notes [Member] | 10 1/2% Senior Notes, due 2020 [Member] | Initial Public Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 288,200,000
Senior Notes [Member] | Summit Materials And Summit Materials Finance Corp [Member] | 2020 Notes Additional [Member]
Debt Instrument [Line Items]
Debt instrument, face amount							$ 115,000,000	$ 260,000,000
Proceeds from issuance of debt		409,300,000
Premium of debt instrument	34,300,000	34,300,000
Senior Notes [Member] | Summit Materials And Summit Materials Finance Corp [Member] | Existing Secured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	250,000,000	250,000,000
Senior Notes [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Refinance of existing senior secured term loan facility					$ 183,000,000
Senior Notes [Member] | Summit Materials, LLC [Member] | Davenport Acquisition [Member]
Debt Instrument [Line Items]
Initial purchase price		370,000,000
Senior Notes [Member] | Summit Materials, LLC [Member] | 6 1/8% Senior Notes, due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 350,000,000	$ 350,000,000
Senior notes, interest rate	6.125%	6.125%
Percentage of par value of senior notes		100.00%
Debt instrument maturity year		Jul. 15, 2023
Notes payable commencing date		Jan. 15, 2016
Senior Notes [Member] | Summit Materials, LLC [Member] | 10 1/2% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, amount redeemed		$ 183,000,000
Charges on redemption	$ 14,100,000	45,400,000
Debt Instrument, redemption premium	18,200,000	56,400,000
Write off of deferred financing fees	2,800,000	7,500,000
Net benefit from the write-off the original issuance premium and discount	$ 6,900,000	$ 18,500,000
Senior Notes [Member] | Summit Materials, LLC [Member] | 10 1/2% Senior Notes, due 2020 [Member] | Initial Public Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 288,200,000

Debt - Senior Secured Credit Fa

Debt - Senior Secured Credit Facilities - Additional Information (Detail) - USD ($)	Jul. 17, 2015	Mar. 17, 2015	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Jul. 16, 2015	Mar. 16, 2015	Mar. 11, 2015
Debt Instrument [Line Items]
Financing fees			$ (32,641,000)		$ (64,313,000)
Outstanding letters of credit			60,000,000		60,000,000
Interest expense			$ 17,800,000	$ 19,900,000	$ 54,600,000	$ 56,400,000
Senior Secured Credit Facilities [Member] | Maximum [Member]
Debt Instrument [Line Items]
First lien leverage ratio					4.751
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 235,000,000						$ 150,000,000
Revolving credit facility, maturity date		Mar. 11, 2020
Effective interest rate			3.20%		3.20%
Outstanding letters of credit			$ 60,000,000		$ 60,000,000
Revolving Credit Facility [Member] | Federal Funds Effective Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%
Revolving Credit Facility [Member] | Libor Plus Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					1.00%
Revolving Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Interest rate - Revolving credit commitments, minimum interest rate					2.00%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					3.00%
Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			150,600,000		$ 150,600,000
Outstanding letters of credit			24,400,000		24,400,000
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Financing fees			(32,641,000)		(64,313,000)
Outstanding letters of credit			60,000,000		60,000,000
Interest expense			17,800,000	$ 19,900,000	54,600,000	$ 56,400,000
Summit Materials, LLC [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			650,000,000		$ 650,000,000
Quarterly principal repayments percentage					0.25%
Frequency of periodic payment					Term debt are due on the last business day of each March, June, September and December
Maturity date					Jul. 17, 2022
Basis spread description	25 basis point
Summit Materials, LLC [Member] | Senior Secured Credit Facilities [Member] | Maximum [Member]
Debt Instrument [Line Items]
First lien leverage ratio					4.751
Summit Materials, LLC [Member] | Senior Secured Credit Facilities [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	2.25%
Summit Materials, LLC [Member] | Senior Secured Credit Facilities [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	3.25%
Summit Materials, LLC [Member] | Senior Secured Credit Facilities [Member] | Libor Floor Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Summit Materials, LLC [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			235,000,000		$ 235,000,000
Line of credit facility, maximum borrowing capacity		$ 235,000,000							$ 150,000,000
Revolving credit facility, maturity date		Mar. 11, 2020
Outstanding letters of credit			$ 60,000,000		$ 60,000,000
Summit Materials, LLC [Member] | Revolving Credit Facility [Member] | Federal Funds Effective Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%
Summit Materials, LLC [Member] | Revolving Credit Facility [Member] | Libor Plus Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					1.00%
Effective interest rate			3.60%		3.60%
Summit Materials, LLC [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Interest rate - Revolving credit commitments, minimum interest rate					2.50%
Summit Materials, LLC [Member] | Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate					3.50%
Summit Materials, LLC [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 150,600,000		$ 150,600,000
Outstanding letters of credit			24,400,000		24,400,000
Summit Materials, LLC [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 650,000,000		$ 650,000,000
Summit Materials, LLC [Member] | Term Loan Facility [Member] | Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 422,000,000
Line of credit facility, maximum borrowing capacity	$ 650,000,000						$ 422,000,000

Debt - Summary of Activity for

Debt - Summary of Activity for Deferred Financing Fees (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Deferred Financing Cost [Line Items]
Beginning balance	$ 17,215	$ 11,485
Loan origination fees	10,911	9,281
Amortization	(2,731)	(2,875)
Write off of deferred financing fees	(12,135)
Ending balance	13,260	17,891
Summit Materials, LLC [Member]
Deferred Financing Cost [Line Items]
Beginning balance	17,215	11,485
Loan origination fees	10,911	9,281
Amortization	(2,731)	(2,875)
Write off of deferred financing fees	(12,135)
Ending balance	$ 13,260	$ 17,891

Debt - Other - Additional Infor

Debt - Other - Additional Information (Detail) - Other [Member] CAD in Millions	Jan. 15, 2015CAD
Columbia [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Prime rate	0.20%
Columbia [Member] | Prime Rate [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Prime rate	0.20%
Canada [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Prime rate	0.90%
Canada [Member] | Prime Rate [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Prime rate	0.90%
Revolving Credit Facility [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Revolving credit commitment	CAD 0.4
Revolving Credit Facility [Member] | Columbia [Member]
Debt Instrument [Line Items]
Revolving credit commitment	6
Revolving Credit Facility [Member] | Columbia [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Revolving credit commitment	6
Revolving Credit Facility [Member] | Canada [Member]
Debt Instrument [Line Items]
Revolving credit commitment	0.5
Revolving Credit Facility [Member] | Canada [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Revolving credit commitment	0.5
Revolving Credit Facility [Member] | Mainland [Member]
Debt Instrument [Line Items]
Revolving credit commitment	CAD 0.4

Accumulated Other Comprehensi56

Accumulated Other Comprehensive Loss - Summary of Changes in Each Component of Accumulated Comprehensive Income Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment				$ 2,164
Foreign currency translation adjustment	$ (6,296)	$ (1,764)	$ (11,531)	(1,764)
Loss on cash flow hedges	(1,010)		(1,010)
Ending balance	(2,607)		(2,607)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment			(2,109)
Ending balance	(2,109)		(2,109)
Cash Flow Hedge Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss on cash flow hedges			(498)
Ending balance	(498)		(498)
Accumulated Other Comprehensive Loss (AOCI) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment			(2,109)
Loss on cash flow hedges			(498)
Ending balance	(2,607)		(2,607)
Summit Materials, LLC [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(15,546)
Postretirement adjustment				2,164
Foreign currency translation adjustment	(6,296)	(1,764)	(11,531)	(1,764)
Loss on cash flow hedges	(1,010)		(1,010)
Ending balance	(28,087)		(28,087)
Summit Materials, LLC [Member] | Pension And Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(9,730)	(6,045)
Ending balance	(9,730)	(5,472)	(9,730)	(5,472)
Summit Materials, LLC [Member] | Pension And Postretirement Plans [Member] | Postretirement Curtailment Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment				(942)
Summit Materials, LLC [Member] | Pension And Postretirement Plans [Member] | Postretirement Liability Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment				1,515
Summit Materials, LLC [Member] | Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(5,816)
Foreign currency translation adjustment			(11,531)	(1,764)
Ending balance	(17,347)	(1,764)	(17,347)	(1,764)
Summit Materials, LLC [Member] | Cash Flow Hedge Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss on cash flow hedges			(1,010)
Ending balance	(1,010)		(1,010)
Summit Materials, LLC [Member] | Accumulated Other Comprehensive Loss (AOCI) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(15,546)	(6,045)
Foreign currency translation adjustment			(11,531)	(1,764)
Loss on cash flow hedges			(1,010)
Ending balance	$ (28,087)	$ (7,236)	$ (28,087)	(7,236)
Summit Materials, LLC [Member] | Accumulated Other Comprehensive Loss (AOCI) [Member] | Postretirement Curtailment Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment				(942)
Summit Materials, LLC [Member] | Accumulated Other Comprehensive Loss (AOCI) [Member] | Postretirement Liability Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment				$ 1,515

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended		9 Months Ended
	Aug. 31, 2015	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Income Taxes [Line Items]
Liabilities for uncertain tax positions		$ 0		$ 0		$ 0		$ 0
Interest and penalties recognized in income tax expense		0	$ 0			0	$ 0
Deferred tax assets, net	$ 249,400,000	50,500,000		50,500,000		50,500,000
Deferred tax liability, intangible assets		69,000,000		69,000,000		69,000,000
Deferred tax liability, book aggregate reserves		6,900,000		6,900,000		6,900,000
Deferred tax liability, fixed assets		10,900,000		10,900,000		10,900,000
Valuation allowance	$ 249,400,000	299,900,000		299,900,000		299,900,000
Provision for income taxes		(2,655,000)	(1,038,000)			$ (12,468,000)	(2,498,000)
Percentage of benefits to be paid on tax receivable agreement						85.00%
Purchase of LP units	18,675,000
Liability percentage to holders	85.00%
Total dividend distribution		23,500,000				$ 39,900,000
Distributions paid in cash to Summit Holdings' partners		14,600,000				26,448,000
Distributions paid in cash to Summit Inc.		8,900,000				13,500,000
Limited Liability Company [Member]
Income Taxes [Line Items]
Provision for income taxes		0				0
Summit Materials, LLC [Member]
Income Taxes [Line Items]
Liabilities for uncertain tax positions		0		0		0		$ 0
Interest and penalties recognized in income tax expense		0	0	$ 0	$ 0
Provision for income taxes		(2,655,000)	$ (1,038,000)			(12,468,000)	$ (2,498,000)
Total dividend distribution		23,500,000				39,900,000
Distributions paid in cash to Summit Holdings' partners		14,600,000				39,952,000
Distributions paid in cash to Summit Inc.		$ 8,900,000				$ 13,500,000

Net Income Per Share - Addition

Net Income Per Share - Additional Information (Detail) - $ / shares	Aug. 11, 2015	Sep. 26, 2015	Sep. 26, 2015	Sep. 26, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic and diluted earnings per share for discontinued operations		$ 0		$ 0.01
Limited Partnership Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti dilutive shares excluded from calcualtion of earnings per share				99,342,035
Stock Option [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti dilutive shares excluded from calcualtion of earnings per share				250,000
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Issuance of common stock, Shares	22,425,000		47,980,555	25,555,555
Class A common shares				1,029,183
Common stock, shares outstanding		49,009,738	49,009,738	49,009,738

Net Income Per Share - Schedule

Net Income Per Share - Schedule of Basic to Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015
Schedule Of Earnings Per Share [Line Items]
Net income attributable to Summit Inc.	$ 14,711	$ 4,355
Basic earnings per share	$ 0.39	$ 0.14
Add: Warrants	43,478	42,909
Weighted average dilutive shares	37,963,930	31,811,315
Diluted earnings per share	$ 0.39	$ 0.14
Common Class A [Member]
Schedule Of Earnings Per Share [Line Items]
Weighted average shares of Class A shares	37,920,452	31,768,406
Basic earnings per share	$ 0.39	$ 0.14
Weighted average shares of Class A shares	37,920,452	31,768,406
Weighted average dilutive shares	37,963,930	31,811,315
Diluted earnings per share	$ 0.39	$ 0.14

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Apr. 02, 2015	Sep. 26, 2015	Dec. 29, 2012	Dec. 31, 2011	Dec. 27, 2014
Loss Contingencies [Line Items]
Percentage of ownership interest in joint venture		40.00%
Amount funded for loss incurred by joint venture		$ 8.8	$ 4	$ 4.8
Accrual recorded in other noncurrent liabilities		4.3			$ 4.3
Value of damages sought	$ 29.4
Unapproved change orders and claims					3.9
Unapproved change orders within accounts receivable		$ 1.2			1.2
Unapproved change orders within costs in excess of billings					0.5
Unapproved change orders within other current assets					2.2
Summit Materials, LLC [Member]
Loss Contingencies [Line Items]
Percentage of ownership interest in joint venture		40.00%
Amount funded for loss incurred by joint venture		$ 8.8	$ 4	$ 4.8
Accrual recorded in other noncurrent liabilities		4.3			4.3
Value of damages sought	$ 29.4
Unapproved change orders and claims					3.9
Unapproved change orders within accounts receivable		$ 1.2			1.2
Unapproved change orders within costs in excess of billings					0.5
Unapproved change orders within other current assets					$ 2.2
Maximum [Member]
Loss Contingencies [Line Items]
Duration of commitments		1 year
Maximum [Member] | Summit Materials, LLC [Member]
Loss Contingencies [Line Items]
Duration of commitments		1 year

Supplemental Cash Flow Inform61

Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Cash payments:
Interest	$ 75,990	$ 59,179
Income taxes	1,516	1,345
Non cash financing activities:
Purchase of noncontrolling interest in Continental Cement	(29,102)
Summit Materials, LLC [Member]
Cash payments:
Interest	75,990	59,179
Income taxes	1,516	$ 1,345
Non cash financing activities:
Purchase of noncontrolling interest in Continental Cement	$ (64,102)

Segment Information - Additiona

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 26, 2015Segment
Segment Reporting Information [Line Items]
Number of operating segments	3
Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Number of operating segments	3

Segment Information - Summary o

Segment Information - Summary of Financial Data for Company's Reportable Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Segment Reporting Information [Line Items]
Total revenue	$ 471,905	$ 394,759	$ 1,030,835	$ 870,145
Adjusted EBITDA	117,834	72,412	182,443	112,901
Total assets	2,330,241		2,330,241		$ 1,729,777
Interest expense	20,727	22,085	62,231	62,555
Total revenue	471,905	394,759	1,030,835	870,145
Depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Initial public offering costs			28,296
Loss on debt financings	32,641		64,313
Income (loss) from continuing operations before taxes	31,160	27,072	(59,215)	(13,604)
Total capital expenditures			69,672	64,244
Total depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	471,905	394,759	1,030,835	870,145
Adjusted EBITDA	117,834	72,412	182,443	112,901
Total assets	2,316,736		2,316,736		1,729,777
Interest expense	20,436	22,085	61,649	62,555
Total revenue	471,905	394,759	1,030,835	870,145
Depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Initial public offering costs			28,296
Loss on debt financings	32,641		64,313
Income (loss) from continuing operations before taxes	31,451	27,072	(58,633)	(13,604)
Total capital expenditures			69,672	64,244
Total depreciation, depletion, amortization and accretion	33,306	23,255	86,818	63,950
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	2,280,801		2,280,801		1,703,713
Depreciation, depletion, amortization and accretion	32,678	22,849	85,132	62,902
Total capital expenditures			65,928	60,571
Total depreciation, depletion, amortization and accretion	32,678	22,849	85,132	62,902
Operating Segments [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total assets	2,280,801		2,280,801		1,703,713
Depreciation, depletion, amortization and accretion	32,678	22,849	85,132	62,902
Total capital expenditures			65,928	60,571
Total depreciation, depletion, amortization and accretion	32,678	22,849	85,132	62,902
Operating Segments [Member] | Aggregates [Member]
Segment Reporting Information [Line Items]
Total revenue	86,070	68,636	218,336	160,002
Total revenue	86,070	68,636	218,336	160,002
Operating Segments [Member] | Aggregates [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	86,070	68,636	218,336	160,002
Total revenue	86,070	68,636	218,336	160,002
Operating Segments [Member] | Cement [Member]
Segment Reporting Information [Line Items]
Total revenue	68,481	34,171	110,477	69,435
Total revenue	68,481	34,171	110,477	69,435
Operating Segments [Member] | Cement [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	68,481	34,171	110,477	69,435
Total revenue	68,481	34,171	110,477	69,435
Operating Segments [Member] | Ready Mixed Concrete [Member]
Segment Reporting Information [Line Items]
Total revenue	95,481	75,429	254,878	189,198
Total revenue	95,481	75,429	254,878	189,198
Operating Segments [Member] | Ready Mixed Concrete [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	95,481	75,429	254,878	189,198
Total revenue	95,481	75,429	254,878	189,198
Operating Segments [Member] | Asphalt [Member]
Segment Reporting Information [Line Items]
Total revenue	113,249	104,862	219,492	203,944
Total revenue	113,249	104,862	219,492	203,944
Operating Segments [Member] | Asphalt [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	113,249	104,862	219,492	203,944
Total revenue	113,249	104,862	219,492	203,944
Operating Segments [Member] | Paving And Related Services [Member]
Segment Reporting Information [Line Items]
Total revenue	185,092	191,157	366,321	391,925
Total revenue	185,092	191,157	366,321	391,925
Operating Segments [Member] | Paving And Related Services [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	185,092	191,157	366,321	391,925
Total revenue	185,092	191,157	366,321	391,925
Operating Segments [Member] | West Region [Member]
Segment Reporting Information [Line Items]
Total revenue	261,742	211,302	597,484	478,432
Adjusted EBITDA	59,574	39,105	110,940	71,646
Total assets	866,516		866,516		777,981
Total revenue	261,742	211,302	597,484	478,432
Depreciation, depletion, amortization and accretion	13,786	9,155	38,508	23,569
Total capital expenditures			32,192	25,496
Total depreciation, depletion, amortization and accretion	13,786	9,155	38,508	23,569
Operating Segments [Member] | West Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	261,742	211,302	597,484	478,432
Adjusted EBITDA	59,574	39,105	110,940	71,646
Total assets	866,516		866,516		777,981
Total revenue	261,742	211,302	597,484	478,432
Depreciation, depletion, amortization and accretion	13,786	9,155	38,508	23,569
Total capital expenditures			32,192	25,496
Total depreciation, depletion, amortization and accretion	13,786	9,155	38,508	23,569
Operating Segments [Member] | Central Region [Member]
Segment Reporting Information [Line Items]
Total revenue	164,084	126,882	338,613	283,541
Adjusted EBITDA	53,756	30,820	89,984	59,220
Total assets	1,189,565		1,189,565		704,134
Total revenue	164,084	126,882	338,613	283,541
Depreciation, depletion, amortization and accretion	15,778	9,710	37,198	28,061
Total capital expenditures			24,335	28,485
Total depreciation, depletion, amortization and accretion	15,778	9,710	37,198	28,061
Operating Segments [Member] | Central Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	164,084	126,882	338,613	283,541
Adjusted EBITDA	53,756	30,820	89,984	59,220
Total assets	1,189,565		1,189,565		704,134
Total revenue	164,084	126,882	338,613	283,541
Depreciation, depletion, amortization and accretion	15,778	9,710	37,198	28,061
Total capital expenditures			24,335	28,485
Total depreciation, depletion, amortization and accretion	15,778	9,710	37,198	28,061
Operating Segments [Member] | East Region [Member]
Segment Reporting Information [Line Items]
Total revenue	46,079	56,575	94,738	108,172
Adjusted EBITDA	13,383	11,868	15,096	10,462
Total assets	224,720		224,720		221,598
Total revenue	46,079	56,575	94,738	108,172
Depreciation, depletion, amortization and accretion	3,114	3,984	9,426	11,272
Total capital expenditures			9,401	6,590
Total depreciation, depletion, amortization and accretion	3,114	3,984	9,426	11,272
Operating Segments [Member] | East Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	46,079	56,575	94,738	108,172
Adjusted EBITDA	13,383	11,868	15,096	10,462
Total assets	224,720		224,720		221,598
Total revenue	46,079	56,575	94,738	108,172
Depreciation, depletion, amortization and accretion	3,114	3,984	9,426	11,272
Total capital expenditures			9,401	6,590
Total depreciation, depletion, amortization and accretion	3,114	3,984	9,426	11,272
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue	(76,468)	(79,496)	(138,669)	(144,359)
Total revenue	(76,468)	(79,496)	(138,669)	(144,359)
Intersegment Eliminations [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	(76,468)	(79,496)	(138,669)	(144,359)
Total revenue	(76,468)	(79,496)	(138,669)	(144,359)
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA	(8,879)	(9,381)	(33,577)	(28,427)
Total assets	49,440		49,440		26,064
Depreciation, depletion, amortization and accretion	628	406	1,686	1,048
Total capital expenditures			3,744	3,673
Total depreciation, depletion, amortization and accretion	628	406	1,686	1,048
Corporate and Other [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA	(8,879)	(9,381)	(33,577)	(28,427)
Total assets	35,935		35,935		$ 26,064
Depreciation, depletion, amortization and accretion	628	406	1,686	1,048
Total capital expenditures			3,744	3,673
Total depreciation, depletion, amortization and accretion	$ 628	$ 406	$ 1,686	$ 1,048

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail)

Sep. 26, 2015USD ($)

Aug. 13, 2015USD ($)

Jul. 17, 2015USD ($)Business

Sep. 30, 2014USD ($)

Jan. 31, 2014USD ($)

Mar. 11, 2015USD ($)

Mar. 17, 2015USD ($)

Sep. 27, 2014USD ($)

Sep. 26, 2015USD ($)

Sep. 27, 2014USD ($)

Dec. 28, 2014USD ($)

Dec. 27, 2014USD ($)

Related Party Transaction [Line Items]

Assets sold to related party

$ 2,300,000

Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Net cash paid for acquisitions

$ 448,710,000

$ 448,710,000

Summit Materials, LLC [Member]

Related Party Transaction [Line Items]

Assets sold to related party

2,300,000

Summit Materials, LLC [Member] | Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Net cash paid for acquisitions

$ 448,710,000

448,710,000

Blackstone Management Partners L.L.C. [Member]

Related Party Transaction [Line Items]

Consideration of Consolidated profit

Greater of $300,000 or 2.0%

Payment for services

$ 300,000

Threshold of annual consolidated profits

2.00%

Management fees incurred

$ 1,000,000

$ 1,300,000

2,300,000

Percentage transaction fee on value of entity acquired

1.00%

Consideration paid / received on assets acquired / disposed

1.00%

1.00%

Transaction fees paid

600,000

2,300,000

Management fee agreement termination date

Mar. 17, 2015

Management fee paid as of termination

$ 13,800,000

Related party transactions

$ 5,750,000

$ 13,000,000

Blackstone Management Partners L.L.C. [Member] | Summit Materials, LLC [Member]

Related Party Transaction [Line Items]

Consideration of Consolidated profit

Greater of $300,000 or 2.0%

Payment for services

$ 300,000

Threshold of annual consolidated profits

2.00%

Management fees incurred

$ 1,000,000

1,300,000

2,300,000

Percentage transaction fee on value of entity acquired

1.00%

Consideration paid / received on assets acquired / disposed

1.00%

1.00%

Transaction fees paid

600,000

2,300,000

Management fee agreement termination date

Mar. 17, 2015

Management fee paid as of termination

$ 13,800,000

Related party transactions

$ 5,750,000

$ 13,000,000

Blackstone and Affiliates [Member]

Related Party Transaction [Line Items]

Management fee paid as of termination

13,400,000

Blackstone and Affiliates [Member] | Summit Materials, LLC [Member]

Related Party Transaction [Line Items]

Management fee paid as of termination

13,400,000

Silverhawk Summit LP [Member]

Related Party Transaction [Line Items]

Management fee paid as of termination

400,000

Silverhawk Summit LP [Member] | Summit Materials, LLC [Member]

Related Party Transaction [Line Items]

Management fee paid as of termination

400,000

Lafarge North America Inc [Member] | Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Net cash paid for acquisitions

$ 448,710,000

Purchase agreement date for assets acquired

Apr. 16, 2015

Purchase price paid

$ 370,000,000

$ 80,000,000

Lafarge North America Inc [Member] | Bettendorf Iowa [Member]

Related Party Transaction [Line Items]

Number of cement distribution terminals acquired | Business

1

Lafarge North America Inc [Member] | Summit Materials, LLC [Member] | Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Net cash paid for acquisitions

$ 448,710,000

Purchase agreement date for assets acquired

Apr. 16, 2015

Purchase price paid

$ 370,000,000

$ 80,000,000

Lafarge North America Inc [Member] | Summit Materials, LLC [Member] | Bettendorf Iowa [Member]

Related Party Transaction [Line Items]

Number of cement distribution terminals acquired | Business

1

Blackstone Capital Partners VI Limited Partnership [Member] | Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Equity commitment financing

$ 90,000,000

Deferred purchase price associated with acquisition

80,000,000

Commitment fee paid

1,800,000

Blackstone Capital Partners VI Limited Partnership [Member] | Summit Materials, LLC [Member] | Davenport Acquisition [Member]

Related Party Transaction [Line Items]

Equity commitment financing

90,000,000

Deferred purchase price associated with acquisition

$ 80,000,000

Commitment fee paid

$ 1,800,000

Continental Cement Company, L.L.C. [Member]

Related Party Transaction [Line Items]

Sales to related parties

$ 1,400,000

4,700,000

10,900,000

Accounts receivables due from related parties

$ 200,000

Non controlling interest owned

700,000

Continental Cement Company, L.L.C. [Member] | Summit Materials, LLC [Member]

Related Party Transaction [Line Items]

Sales to related parties

$ 1,400,000

$ 4,700,000

10,900,000

Accounts receivables due from related parties

$ 200,000

Non controlling interest owned

$ 700,000

Guarantor and Non-Guarantor F65

Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Current assets:
Cash and cash equivalents	$ 18,987	$ 13,215
Accounts receivable, net	205,939	141,302
Cost and estimated earnings in excess of billings	34,175	10,174
Inventories	138,036	111,553
Other current assets	21,762	17,172
Total current assets	418,899	293,416
Property, plant and equipment, net	1,276,227	950,601
Goodwill	567,836	419,270
Intangible assets, net	15,481	17,647
Other assets	51,798	48,843
Total assets	2,330,241	1,729,777
Current liabilities:
Current portion of debt	68,125	5,275
Current portion of acquisition-related liabilities	20,191	18,402
Accounts payable	113,226	78,854
Accrued expenses	90,880	101,496
Billings in excess of costs and estimated earnings	11,005	8,958
Total current liabilities	303,427	212,985
Long-term debt	1,148,068	1,059,642
Acquisition-related liabilities	41,978	42,736
Other noncurrent liabilities	114,575	93,691
Total liabilities	1,608,048	1,409,054
Redeemable noncontrolling interest		33,740	$ 286,817
Total liabilities, redeemable noncontrolling interest and member's interest	2,330,241	1,729,777
Summit Materials, LLC [Member]
Current assets:
Cash and cash equivalents	5,482	13,215
Accounts receivable, net	205,939	141,302
Cost and estimated earnings in excess of billings	34,175	10,174
Inventories	138,036	111,553
Other current assets	21,762	17,172
Total current assets	405,394	293,416
Property, plant and equipment, net	1,276,227	950,601
Goodwill	567,836	419,270
Intangible assets, net	15,481	17,647
Other assets	51,798	48,843
Total assets	2,316,736	1,729,777
Current liabilities:
Current portion of debt	68,125	5,275
Current portion of acquisition-related liabilities	17,691	18,402
Accounts payable	113,226	78,854
Accrued expenses	90,880	101,496
Billings in excess of costs and estimated earnings	11,005	8,958
Total current liabilities	300,927	212,985
Long-term debt	1,148,068	1,059,642
Acquisition-related liabilities	33,320	42,736
Other noncurrent liabilities	114,575	93,691
Total liabilities	1,596,890	1,409,054
Redeemable noncontrolling interest		33,740
Total stockholders' equity/partners' interest	719,846	286,983
Total liabilities, redeemable noncontrolling interest and member's interest	2,316,736	1,729,777
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Current assets:
Cash and cash equivalents	(12,662)	(7,112)
Accounts receivable, net	(344)	(1,233)
Intercompany receivables	(1,345,915)	(415,030)
Other current assets		(1,853)
Total current assets	(1,358,921)	(425,228)
Other assets	(963,928)	(1,256,418)
Total assets	(2,322,849)	(1,681,646)
Current liabilities:
Current portion of debt		(5,263)
Accounts payable	(344)	(1,233)
Accrued expenses	(12,662)	(8,965)
Intercompany payables	(1,345,915)	(415,030)
Total current liabilities	(1,358,921)	(430,491)
Long-term debt	(61,377)	(633,917)
Other noncurrent liabilities	(55,107)	(55,107)
Total liabilities	(1,475,405)	(1,119,515)
Redeemable noncontrolling interest		33,740
Redeemable members' interest		(34,543)
Total stockholders' equity/partners' interest	(847,444)	(561,328)
Total liabilities, redeemable noncontrolling interest and member's interest	(2,322,849)	(1,681,646)
Summit Materials, LLC [Member] | Issuers [Member]
Current assets:
Cash and cash equivalents	8,989	10,837
Accounts receivable, net		1
Intercompany receivables	1,322,050	376,344
Other current assets	1,088	7,148
Total current assets	1,332,127	394,330
Property, plant and equipment, net	9,433	7,035
Other assets	881,923	1,153,204
Total assets	2,223,483	1,554,569
Current liabilities:
Current portion of debt	68,125	5,275
Current portion of acquisition-related liabilities		166
Accounts payable	7,436	3,655
Accrued expenses	30,998	37,101
Intercompany payables	67,671	162,728
Total current liabilities	174,230	208,925
Long-term debt	1,148,068	1,059,642
Other noncurrent liabilities	1,558	796
Total liabilities	1,323,856	1,269,363
Total stockholders' equity/partners' interest	899,627	285,206
Total liabilities, redeemable noncontrolling interest and member's interest	2,223,483	1,554,569
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Current assets:
Cash and cash equivalents	1,025	695
Accounts receivable, net	195,120	124,380
Intercompany receivables	14,869	30,539
Cost and estimated earnings in excess of billings	33,447	9,819
Inventories	132,734	98,188
Other current assets	19,319	9,638
Total current assets	396,514	273,259
Property, plant and equipment, net	1,240,126	610,717
Goodwill	519,759	340,969
Intangible assets, net	14,044	14,245
Other assets	132,532	125,462
Total assets	2,302,975	1,364,652
Current liabilities:
Current portion of debt		3,990
Current portion of acquisition-related liabilities	17,691	18,236
Accounts payable	102,571	65,018
Accrued expenses	70,386	59,477
Intercompany payables	1,274,510	245,416
Billings in excess of costs and estimated earnings	10,983	8,931
Total current liabilities	1,476,141	401,068
Long-term debt	61,377	480,599
Acquisition-related liabilities	33,320	42,736
Other noncurrent liabilities	110,856	65,479
Total liabilities	1,681,694	989,882
Total stockholders' equity/partners' interest	621,281	374,770
Total liabilities, redeemable noncontrolling interest and member's interest	2,302,975	1,364,652
Summit Materials, LLC [Member] | Non Guarantor [Member]
Current assets:
Cash and cash equivalents	8,130	8,793
Accounts receivable, net	11,163	11,525
Intercompany receivables	8,996	4,052
Cost and estimated earnings in excess of billings	728	355
Inventories	5,302	4,669
Other current assets	1,355	1,775
Total current assets	35,674	31,169
Property, plant and equipment, net	26,668	30,325
Goodwill	48,077	55,177
Intangible assets, net	1,437	2,860
Other assets	1,271	1,362
Total assets	113,127	120,893
Current liabilities:
Accounts payable	3,563	4,569
Accrued expenses	2,158	3,705
Intercompany payables	3,734	2,834
Billings in excess of costs and estimated earnings	22	27
Total current liabilities	9,477	11,135
Other noncurrent liabilities	57,268	57,736
Total liabilities	66,745	68,871
Total stockholders' equity/partners' interest	46,382	52,022
Total liabilities, redeemable noncontrolling interest and member's interest	$ 113,127	120,893
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Current assets:
Cash and cash equivalents		2
Accounts receivable, net		6,629
Intercompany receivables		4,095
Inventories		8,696
Other current assets		464
Total current assets		19,886
Property, plant and equipment, net		302,524
Goodwill		23,124
Intangible assets, net		542
Other assets		25,233
Total assets		371,309
Current liabilities:
Current portion of debt		1,273
Accounts payable		6,845
Accrued expenses		10,178
Intercompany payables		4,052
Total current liabilities		22,348
Long-term debt		153,318
Other noncurrent liabilities		24,787
Total liabilities		200,453
Redeemable members' interest		34,543
Total stockholders' equity/partners' interest		136,313
Total liabilities, redeemable noncontrolling interest and member's interest		$ 371,309

Guarantor and Non-Guarantor F66

Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		7 Months Ended	9 Months Ended
	Mar. 11, 2015	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 26, 2015	Sep. 27, 2014
Condensed Financial Statements, Captions [Line Items]
Revenue		$ 471,905	$ 394,759		$ 1,030,835	$ 870,145
Cost of revenue (excluding items shown separately below)		312,399	285,497		719,838	645,934
Depreciation, depletion, amortization and accretion		33,306	23,255		86,818	63,950
Operating income (loss)		83,357	47,749		66,651	46,652
Interest expense		20,727	22,085		62,231	62,555
Income (loss) from continuing operations before taxes		31,160	27,072		(59,215)	(13,604)
Income tax benefit (expense)		(2,655)	(1,038)		(12,468)	(2,498)
(Loss) income from continuing operations		33,815	28,110		(46,747)	(11,106)
Income from discontinued operations		(57)	(7)		(815)	(356)
Net income (loss)	$ (41,415)	33,872	28,117	$ (2,627)	(45,932)	(10,750)
Net income (loss) attributable to member of Summit Materials, LLC		14,711			4,355
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		12,090			1,748
Summit Materials, LLC [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue		471,905	394,759		1,030,835	870,145
Cost of revenue (excluding items shown separately below)		312,399	285,497		719,838	645,934
General and administrative expenses		42,843	38,258		157,528	113,609
Depreciation, depletion, amortization and accretion		33,306	23,255		86,818	63,950
Operating income (loss)		83,357	47,749		66,651	46,652
Other (income) expense, net		31,470	(1,408)		63,635	(2,299)
Interest expense		20,436	22,085		61,649	62,555
Income (loss) from continuing operations before taxes		31,451	27,072		(58,633)	(13,604)
Income tax benefit (expense)		(2,655)	(1,038)		(12,468)	(2,498)
(Loss) income from continuing operations		34,106	28,110		(46,165)	(11,106)
Income from discontinued operations		(57)	(7)		(815)	(356)
Net income (loss)		34,163	28,117		(45,350)	(10,750)
Net income (loss) attributable to minority interest		52	1,243		(1,917)	674
Net income (loss) attributable to member of Summit Materials, LLC		34,111	26,874		(43,433)	(11,424)
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		26,805	25,110		(55,974)	(12,615)
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue		(4,068)	(10,823)		(28,139)	(19,692)
Cost of revenue (excluding items shown separately below)		(4,068)	(10,823)		(28,139)	(19,692)
Other (income) expense, net		86,514	46,119		111,436	40,369
Interest expense		(10,796)	(2,408)		(21,568)	(5,934)
Income (loss) from continuing operations before taxes		(75,718)	(43,711)		(89,868)	(34,435)
(Loss) income from continuing operations		(75,718)	(43,711)		(89,868)	(34,435)
Net income (loss)		(75,718)	(43,711)		(89,868)	(34,435)
Net income (loss) attributable to minority interest		52	1,243		(1,917)	674
Net income (loss) attributable to member of Summit Materials, LLC		(75,770)	(44,954)		(87,951)	(35,109)
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		(68,464)	(43,190)		(75,410)	(34,163)
Summit Materials, LLC [Member] | Issuers [Member]
Condensed Financial Statements, Captions [Line Items]
General and administrative expenses		8,881	8,694		61,634	26,384
Depreciation, depletion, amortization and accretion		628	406		1,686	1,047
Operating income (loss)		(9,509)	(9,100)		(63,320)	(27,431)
Other (income) expense, net		(58,666)	(43,887)		(55,083)	(36,161)
Interest expense		15,046	7,913		35,196	21,581
Income (loss) from continuing operations before taxes		34,111	26,874		(43,433)	(12,851)
Income tax benefit (expense)						(1,427)
(Loss) income from continuing operations		34,111	26,874		(43,433)	(11,424)
Net income (loss)		34,111	26,874		(43,433)	(11,424)
Net income (loss) attributable to member of Summit Materials, LLC		34,111	26,874		(43,433)	(11,424)
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		26,805	25,110		(55,974)	(12,615)
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue		454,501	348,785		980,153	776,502
Cost of revenue (excluding items shown separately below)		304,204	253,284		696,068	581,602
General and administrative expenses		32,362	27,418		90,959	80,938
Depreciation, depletion, amortization and accretion		31,374	18,618		80,997	51,351
Operating income (loss)		86,561	49,465		112,129	62,611
Other (income) expense, net		3,639	(2,679)		7,140	(4,233)
Interest expense		15,286	13,416		45,332	37,831
Income (loss) from continuing operations before taxes		67,636	38,728		59,657	29,013
Income tax benefit (expense)		(2,690)	(1,038)		(12,852)	(1,071)
(Loss) income from continuing operations		70,326	39,766		72,509	30,084
Income from discontinued operations		(57)	(7)		(815)	(356)
Net income (loss)		70,383	39,773		73,324	30,440
Net income (loss) attributable to member of Summit Materials, LLC		70,383	39,773		73,324	30,440
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		69,373	39,773		72,314	30,440
Summit Materials, LLC [Member] | Non Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue		21,472	22,626		78,821	43,900
Cost of revenue (excluding items shown separately below)		12,263	17,433		51,909	30,795
General and administrative expenses		1,600	495		4,935	1,062
Depreciation, depletion, amortization and accretion		1,304	523		4,135	1,068
Operating income (loss)		6,305	4,175		17,842	10,975
Other (income) expense, net		(17)	(16)		142	29
Interest expense		900	233		2,689	289
Income (loss) from continuing operations before taxes		5,422	3,958		15,011	10,657
Income tax benefit (expense)		35			384
(Loss) income from continuing operations		5,387	3,958		14,627	10,657
Net income (loss)		5,387	3,958		14,627	10,657
Net income (loss) attributable to member of Summit Materials, LLC		5,387	3,958		14,627	10,657
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC		$ (909)	2,194		$ 3,096	8,893
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue			34,171			69,435
Cost of revenue (excluding items shown separately below)			25,603			53,229
General and administrative expenses			1,651			5,225
Depreciation, depletion, amortization and accretion			3,708			10,484
Operating income (loss)			3,209			497
Other (income) expense, net			(945)			(2,303)
Interest expense			2,931			8,788
Income (loss) from continuing operations before taxes			1,223			(5,988)
(Loss) income from continuing operations			1,223			(5,988)
Net income (loss)			1,223			(5,988)
Net income (loss) attributable to member of Summit Materials, LLC			1,223			(5,988)
Comprehensive income (loss) attributable to Summit Materials, Inc. and Summit Materials, LLC			$ 1,223			$ (5,170)

Guarantor and Non-Guarantor F67

Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015	Sep. 27, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		$ (18,927)	$ (10,836)
Cash flow from investing activities:
Acquisitions, net of cash acquired		(505,466)	(351,941)
Purchase of property, plant and equipment		(69,672)	(64,244)
Proceeds from the sale of property, plant, and equipment		8,883	9,575
Other		610	757
Net cash (used for) provided by investing activities		(565,645)	(405,853)
Cash flow from financing activities:
Capital issuance costs		(61,218)
Net proceeds from debt issuance		1,415,750	657,217
Payments on long-term debt		(1,251,407)	(258,337)
Payments on acquisition-related liabilities		(15,018)	(5,807)
Financing costs		(10,911)	(8,834)
Distributions from partnership	$ (14,600)	(26,448)
Other			(88)
Net cash provided by (used for) financing activities		590,344	408,501
Net increase (decrease) in cash		5,772	(8,188)
Cash - beginning of period		13,215	18,184
Cash - end of period	18,987	18,987	9,996
Summit Materials, LLC [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		(18,927)	(10,836)
Cash flow from investing activities:
Acquisitions, net of cash acquired		(505,466)	(351,941)
Purchase of property, plant and equipment		(69,672)	(64,244)
Proceeds from the sale of property, plant, and equipment		8,883	9,575
Other		610	757
Net cash (used for) provided by investing activities		(565,645)	(405,853)
Cash flow from financing activities:
Proceeds from investment by member		490,916	24,350
Capital issuance costs		(12,539)
Net proceeds from debt issuance		1,415,750	657,217
Payments on long-term debt		(1,251,407)	(258,337)
Payments on acquisition-related liabilities		(15,018)	(5,807)
Financing costs		(10,911)	(8,834)
Distributions from partnership	(14,600)	(39,952)
Other			(88)
Net cash provided by (used for) financing activities		576,839	408,501
Net increase (decrease) in cash		(7,733)	(8,188)
Cash - beginning of period		13,215	14,917
Cash - end of period	5,482	5,482	6,729
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		(167)	(1,319)
Cash flow from investing activities:
Other			1,166
Net cash (used for) provided by investing activities			1,166
Cash flow from financing activities:
Proceeds from investment by member			(1,353)
Loans received from and payments made on loans from other Summit Companies		(6,439)	(7,923)
Payments on long-term debt		1,056
Other			1,500
Net cash provided by (used for) financing activities		(5,383)	(7,776)
Net increase (decrease) in cash		(5,550)	(7,929)
Cash - beginning of period		(7,112)	(2,540)
Cash - end of period	(12,662)	(12,662)	(10,469)
Summit Materials, LLC [Member] | Issuers [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		(140,504)	(36,504)
Cash flow from investing activities:
Acquisitions, net of cash acquired			(181,754)
Purchase of property, plant and equipment		(3,743)	(3,674)
Net cash (used for) provided by investing activities		(3,743)	(185,428)
Cash flow from financing activities:
Proceeds from investment by member		490,916	24,350
Capital issuance costs		(12,539)
Net proceeds from debt issuance		1,415,750	657,217
Loans received from and payments made on loans from other Summit Companies		(1,031,576)	(195,590)
Payments on long-term debt		(669,123)	(251,062)
Payments on acquisition-related liabilities		(166)	(1,500)
Financing costs		(10,911)	(8,834)
Distributions from partnership		(39,952)
Other			(88)
Net cash provided by (used for) financing activities		142,399	224,493
Net increase (decrease) in cash		(1,848)	2,561
Cash - beginning of period		10,837	10,375
Cash - end of period	8,989	8,989	12,936
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities			(2,408)
Cash flow from investing activities:
Purchase of property, plant and equipment			(13,472)
Net cash (used for) provided by investing activities			(13,472)
Cash flow from financing activities:
Loans received from and payments made on loans from other Summit Companies			16,383
Payments on long-term debt			(509)
Net cash provided by (used for) financing activities			15,874
Net increase (decrease) in cash			(6)
Cash - beginning of period			9
Cash - end of period			3
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		112,541	28,727
Cash flow from investing activities:
Acquisitions, net of cash acquired		(505,466)	(170,187)
Purchase of property, plant and equipment		(65,001)	(46,575)
Proceeds from the sale of property, plant, and equipment		8,821	9,345
Other		610	(409)
Net cash (used for) provided by investing activities		(561,036)	(207,826)
Cash flow from financing activities:
Loans received from and payments made on loans from other Summit Companies		1,047,015	189,243
Payments on long-term debt		(583,340)	(6,766)
Payments on acquisition-related liabilities		(14,852)	(4,307)
Other			(1,500)
Net cash provided by (used for) financing activities		448,823	176,670
Net increase (decrease) in cash		328	(2,429)
Cash - beginning of period		697	3,442
Cash - end of period	1,025	1,025	1,013
Summit Materials, LLC [Member] | Non Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		9,203	668
Cash flow from investing activities:
Purchase of property, plant and equipment		(928)	(523)
Proceeds from the sale of property, plant, and equipment		62	230
Net cash (used for) provided by investing activities		(866)	(293)
Cash flow from financing activities:
Proceeds from investment by member			1,353
Loans received from and payments made on loans from other Summit Companies		(9,000)	(2,113)
Net cash provided by (used for) financing activities		(9,000)	(760)
Net increase (decrease) in cash		(663)	(385)
Cash - beginning of period		8,793	3,631
Cash - end of period	8,130	8,130	$ 3,246
Summit Materials, LLC [Member] | Wholly and Non Wholly Owned Guarantor [Member]
Cash flow from financing activities:
Net increase (decrease) in cash		328
Cash - beginning of period		697
Cash - end of period	$ 1,025	$ 1,025