Summit Materials (SUM) 10-Q 5 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	0 Months Ended	3 Months Ended
	Mar. 28, 2015	Mar. 28, 2015	Apr. 29, 2015
Document Information [Line Items]
Document Type		10-Q
Amendment Flag		FALSE
Document Period End Date		28-Mar-15
Document Fiscal Year Focus		2015
Document Fiscal Period Focus		Q1
Trading Symbol		SUM
Entity Registrant Name		SUMMIT MATERIALS, INC.
Entity Central Index Key		1621563
Current Fiscal Year End Date		-14
Entity Filer Category		Non-accelerated Filer
Membership interests description	As of April 29, 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			26,584,738
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		28-Mar-15
Document Fiscal Year Focus		2015
Document Fiscal Period Focus		Q1
Entity Registrant Name		SUMMIT MATERIALS, LLC
Entity Central Index Key		1571371
Current Fiscal Year End Date		-14
Entity Filer Category		Non-accelerated Filer
Membership interests percentage			100.00%

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Current assets:
Cash	$314,980	$13,215
Accounts receivable, net	109,941	141,302
Costs and estimated earnings in excess of billings	11,836	10,174
Inventories	133,307	111,553
Other current assets	17,476	17,172
Total current assets	587,540	293,416
Property, plant and equipment, less accumulated depreciation, depletion and amortization (March 28, 2015 - $297,187 and December 27, 2014 - $279,375)	948,129	950,601
Goodwill	415,582	419,270
Intangible assets, less accumulated amortization (March 28, 2015 - $3,623 and December 27, 2014 - $3,073)	16,891	17,647
Other assets	50,112	48,843
Total assets	2,018,254	1,729,777
Current liabilities:
Current portion of debt	5,275	5,275
Current portion of acquisition-related liabilities	24,851	18,402
Accounts payable	70,840	78,854
Accrued expenses	81,612	101,496
Billings in excess of costs and estimated earnings	8,309	8,958
Total current liabilities	190,887	212,985
Long-term debt	1,057,418	1,059,642
Acquisition-related liabilities	44,245	42,736
Other noncurrent liabilities	97,433	93,691
Total liabilities	1,389,983	1,409,054
Commitments and contingencies
Redeemable noncontrolling interest		33,740
Stockholders' Equity/Partners' Interest:
Accumulated deficit	-10,151
Accumulated other comprehensive loss	-1,050
Partners' interest		285,685
Additional paid-in capital	456,406
Stockholders' equity/partners' interest:	446,161	285,685
Total liabilities, redeemable noncontrolling interest and member's interest	2,018,254	1,729,777
Total stockholders' equity/partners' interest	628,271	286,983
Common Class A [Member]
Stockholders' Equity/Partners' Interest:
Class A common stock, par value $0.01 per share; 1,000,000,000 shares authorized, 26,584,738 shares issued and outstanding as of March 28, 2015	266
Total stockholders' equity/partners' interest	266
Common Class B [Member]
Stockholders' Equity/Partners' Interest:
Class A common stock, par value $0.01 per share; 1,000,000,000 shares authorized, 26,584,738 shares issued and outstanding as of March 28, 2015	690
Total stockholders' equity/partners' interest	690
Summit Materials, LLC [Member]
Current assets:
Cash	314,980	13,215
Accounts receivable, net	109,941	141,302
Costs and estimated earnings in excess of billings	11,836	10,174
Inventories	133,307	111,553
Other current assets	17,476	17,172
Total current assets	587,540	293,416
Property, plant and equipment, less accumulated depreciation, depletion and amortization (March 28, 2015 - $297,187 and December 27, 2014 - $279,375)	948,129	950,601
Goodwill	415,582	419,270
Intangible assets, less accumulated amortization (March 28, 2015 - $3,623 and December 27, 2014 - $3,073)	16,891	17,647
Other assets	50,112	48,843
Total assets	2,018,254	1,729,777
Current liabilities:
Current portion of debt	5,275	5,275
Current portion of acquisition-related liabilities	22,351	18,402
Accounts payable	70,840	78,854
Accrued expenses	81,612	101,496
Billings in excess of costs and estimated earnings	8,309	8,958
Total current liabilities	188,387	212,985
Long-term debt	1,057,418	1,059,642
Acquisition-related liabilities	36,168	42,736
Other noncurrent liabilities	97,433	93,691
Total liabilities	1,379,406	1,409,054
Commitments and contingencies
Redeemable noncontrolling interest		33,740
Member's interest:
Member's equity	987,010	518,647
Stockholders' Equity/Partners' Interest:
Accumulated deficit	-327,523	-217,416
Accumulated other comprehensive loss	-21,845	-15,546
Member's interest	637,642	285,685
Noncontrolling interest	1,206	1,298
Total member's interest	638,848	286,983
Total liabilities, redeemable noncontrolling interest and member's interest	2,018,254	1,729,777
Noncontrolling interest in consolidated subsidiaries	1,206	1,298
Summit Materials, INC [Member]
Stockholders' Equity/Partners' Interest:
Noncontrolling interest in consolidated subsidiaries	$180,904

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, except Share data, unless otherwise specified
Property, plant and equipment, accumulated depreciation, depletion and amortization	$297,187	$279,375
Intangible assets, accumulated amortization	3,623	3,073
Common Class A [Member]
Common stock, par value	$0.01
Common stock, shares authorized	1,000,000,000
Common stock, shares issued	26,584,738
Common stock, shares outstanding	26,584,738
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	297,187	279,375
Intangible assets, accumulated amortization	$3,623	$3,073

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Revenue:
Product	$148,920	$100,168
Service	26,219	35,851
Net revenue	175,139	136,019
Delivery and subcontract revenue	18,848	15,072
Total revenue	193,987	151,091
Cost of revenue (excluding items shown separately below):
Product	119,791	84,477
Service	19,630	29,126
Net cost of revenue	139,421	113,603
Delivery and subcontract cost	18,848	15,072
Total cost of revenue	158,269	128,675
General and administrative expenses	67,234	35,488
Depreciation, depletion, amortization and accretion	26,126	19,356
Transaction costs	1,364	2,591
Operating (loss) income	-59,006	-35,019
Other expense (income), net	391	-194
Loss on debt financings	799
Interest expense	24,109	18,819
(Loss) income from continuing operations before taxes	-84,305	-53,644
Income tax benefit	-4,468	-596
Loss from continuing operations	-79,837	-53,048
Loss from discontinued operations		20
Net loss	-79,837	-53,068
Net loss per share of Class A common stock:
Net loss	-10,151
Summit Materials, LLC [Member]
Revenue:
Product	148,920	100,168
Service	26,219	35,851
Net revenue	175,139	136,019
Delivery and subcontract revenue	18,848	15,072
Total revenue	193,987	151,091
Cost of revenue (excluding items shown separately below):
Product	119,791	84,477
Service	19,630	29,126
Net cost of revenue	139,421	113,603
Delivery and subcontract cost	18,848	15,072
Total cost of revenue	158,269	128,675
General and administrative expenses	67,234	35,488
Depreciation, depletion, amortization and accretion	26,126	19,356
Transaction costs	1,364	2,591
Operating (loss) income	-59,006	-35,019
Other expense (income), net	391	-194
Loss on debt financings	799
Interest expense	24,109	18,819
(Loss) income from continuing operations before taxes	-84,305	-53,644
Income tax benefit	-4,468	-596
Loss from continuing operations	-79,837	-53,048
Loss from discontinued operations		20
Net loss	-79,837	-53,068
Net loss attributable to noncontrolling interest	-1,982	-2,515
Net loss per share of Class A common stock:
Net loss	67,704	50,553
Summit Holdings [Member]
Net loss per share of Class A common stock:
Net loss	$67,704	$50,553
Common Class A [Member]
Net loss per share of Class A common stock:
Basic	($0.38)
Diluted	($0.38)
Weighted average shares of Class A common stock:
Basic	26,584,738
Diluted	26,584,738

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Net loss	($79,837)	($53,068)
Other comprehensive (loss) income:
Postretirement curtailment adjustment		-1,346
Postretirement liability adjustment		2,164
Foreign currency translation adjustment	-6,299
Other comprehensive (loss) income	-6,299	818
Comprehensive loss	-86,136	-52,250
Comprehensive loss attributable to member of Summit Materials, LLC	-11,201
Summit Materials, LLC [Member]
Net loss	-79,837	-53,068
Other comprehensive (loss) income:
Postretirement curtailment adjustment		-1,346
Postretirement liability adjustment		2,164
Foreign currency translation adjustment	-6,299
Other comprehensive (loss) income	-6,299	818
Comprehensive loss	-86,136	-52,250
Less comprehensive loss attributable to the noncontrolling interest	-1,982	-2,270
Comprehensive loss attributable to member of Summit Materials, LLC	-84,154	-49,980
Summit Holdings [Member]
Other comprehensive (loss) income:
Comprehensive loss attributable to member of Summit Materials, LLC	$72,953	$49,980

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Cash flow from operating activities:
Net loss	($79,837)	($53,068)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	27,358	20,789
Share-based compensation expense	15,217	566
Deferred income tax benefit		-525
Net gain on asset disposals	-1,834	-48
Loss on debt financings	688
Other	780	558
Decrease (increase) in operating assets, net of acquisitions:
Accounts receivable, net	30,309	16,989
Inventories	-21,413	-13,377
Costs and estimated earnings in excess of billings	-1,662	-839
Other current assets	-303	9
Other assets	755	3,202
(Decrease) increase in operating liabilities, net of acquisitions:
Accounts payable	-10,045	-10,239
Accrued expenses	-20,669	-9,620
Billings in excess of costs and estimated earnings	-649	-2,728
Other liabilities	-203	-2,044
Net cash used in operating activities	-61,508	-50,375
Cash flow from investing activities:
Acquisitions, net of cash acquired		-182,514
Purchases of property, plant and equipment	-17,708	-19,941
Proceeds from the sale of property, plant and equipment	2,741	2,202
Other	-276	7
Net cash used for investing activities	-15,243	-200,246
Cash flow from financing activities:
Proceeds from initial public offering	460,000
Capital issuance costs	-35,956
Capital contributions by partners		24,350
Proceeds from debt issuances	104,000	306,750
Debt issuance costs	-4,055	-6,309
Payments on debt	-106,441	-54,314
Purchase of noncontrolling interest in consolidated subsidiary	-35,000
Payments on acquisition-related liabilities	-4,032	-638
Net cash provided by (used for) financing activities	378,516	269,839
Net increase in cash	301,765	19,218
Cash - Beginning of period	13,215	18,184
Cash - end of period	314,980	37,402
Summit Materials, LLC [Member]
Cash flow from operating activities:
Net loss	-79,837	-53,068
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	27,358	20,789
Share-based compensation expense	15,217	566
Deferred income tax benefit		-525
Net gain on asset disposals	-1,834	-48
Loss on debt financings	688
Other	780	558
Decrease (increase) in operating assets, net of acquisitions:
Accounts receivable, net	30,309	16,989
Inventories	-21,413	-13,377
Costs and estimated earnings in excess of billings	-1,662	-839
Other current assets	-303	9
Other assets	755	3,202
(Decrease) increase in operating liabilities, net of acquisitions:
Accounts payable	-10,045	-10,239
Accrued expenses	-20,669	-9,620
Billings in excess of costs and estimated earnings	-649	-2,728
Other liabilities	-203	-2,044
Net cash used in operating activities	-61,508	-50,375
Cash flow from investing activities:
Acquisitions, net of cash acquired		-182,514
Purchases of property, plant and equipment	-17,708	-19,941
Proceeds from the sale of property, plant and equipment	2,741	2,202
Other	-276	7
Net cash used for investing activities	-15,243	-200,246
Cash flow from financing activities:
Capital contributions by member	397,975	24,350
Capital issuance costs	-8,931
Proceeds from debt issuances	104,000	306,750
Debt issuance costs	-4,055	-6,309
Payments on debt	-106,441	-54,314
Payments on acquisition-related liabilities	-4,032	-638
Net cash provided by (used for) financing activities	378,516	269,839
Net increase in cash	301,765	19,218
Cash - Beginning of period	13,215	14,917
Cash - end of period	$314,980	$34,135

Unaudited_Consolidated_Stateme

Unaudited Consolidated Statements of Changes in Redeemable Noncontrolling Interest and Stockholders' Equity (USD $)	Total	Common Class A [Member]	Common Class B [Member]	Redeemable Noncontrolling Interest [Member]	Noncontrolling Interest [Member]	Accumulated Deficit [Member]	AOCI Attributable to Parent [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Materials, LLC [Member]	Summit Holdings [Member]
In Thousands, except Share data									Common Class A [Member]	Common Class B [Member]		Redeemable Noncontrolling Interest [Member]	Noncontrolling Interest [Member]	Accumulated Deficit [Member]	AOCI Attributable to Parent [Member]	Members Equity [Member]	Parent Including Portion Attributable to Non Redeemable Noncontrolling Interest [Member]	Partners Interest [Member]
Beginning Balance at Dec. 28, 2013													$1,211	($198,511)	($6,045)	$486,896	$283,551
Beginning Balance at Dec. 28, 2013	286,817			24,767								24,767	1,211					285,606
Contributed capital, Summit Materials, Inc	24,350																	24,350
Contributed capital, Summit Materials, LLC																24,350	24,350
Accretion/ redemption value adjustment	-2,571			2,571								2,571		-2,571			-2,571	-2,571
Net (loss) income	-53,068			-2,446							-53,068	-2,446	-69	-50,553			-50,622	-50,553
Other comprehensive income (loss)	818			245							818	245			573		573	573
Share-based compensation	566										566					-566	-566	566
Ending Balance at Mar. 29, 2014				25,137								25,137
Ending Balance at Mar. 29, 2014													1,142	-251,635	-5,472	511,812	255,847
Ending Balance at Mar. 29, 2014	259,113												1,142					257,971
Beginning Balance at Dec. 27, 2014	286,983												1,289					285,685
Beginning Balance at Dec. 27, 2014													1,298
Beginning Balance at Dec. 27, 2014	33,740			33,740
Accretion/ redemption value adjustment	-32,252			32,252														-32,252
Net (loss) income	-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				64,102
Ending Balance at Mar. 11, 2015	208,491												1,221					207,270
Beginning Balance at Dec. 27, 2014	286,983												1,289
Beginning Balance at Dec. 27, 2014											286,983		1,298	-217,416	-15,546	518,647	286,983
Beginning Balance at Dec. 27, 2014	33,740										33,740	33,740
Contributed capital, Summit Materials, LLC																453,146	453,146
Accretion/ redemption value adjustment												-31,850		-32,252			-32,252
Net (loss) income	-79,837										-79,837	-1,890	-15	-77,855			-77,947
Other comprehensive income (loss)	-6,299										-6,299				-6,299		-6,299
Share-based compensation	15,217										15,217					-15,217	-15,217
Issuance of common stock, Shares		25,555,555
Ending Balance at Mar. 28, 2015											638,848		1,206	-327,523	-21,845	987,010	638,848
Ending Balance at Mar. 28, 2015	628,271	266											1,206
Ending Balance, Shares at Mar. 28, 2015		26,584,738
Beginning Balance at Mar. 11, 2015	208,491												1,221					207,270
Recording of noncontrolling interest upon reorganization					207,270													-207,270
Net (loss) income	-79,837				-26,366	-10,151							-15
Other comprehensive income (loss)	-6,299						-1,050
Share repurchase, Value	0	0	0		0	0	0	0					0					0
Share repurchase, Shares			100
Purchase of redeemable noncontrolling interest	18,525	10		64,102				18,515
Purchase of redeemable noncontrolling interest, Shares		1,029,183
Share-based compensation	15,217							-14,793
Issuance of common stock, Values	424,044	256	690						423,788	-690
Issuance of common stock, Shares		25,555,555	69,007,397
Ending Balance at Mar. 28, 2015													1,206
Ending Balance at Mar. 28, 2015	$628,271	$266	$690		$180,904	($10,151)	($1,050)	$456,406					$1,206
Ending Balance, Shares at Mar. 28, 2015		26,584,738	69,007,297

Summary_of_Organization_and_Si

Summary of Organization and Significant Accounting Policies	3 Months Ended
	Mar. 28, 2015
Summary of Organization and Significant Accounting Policies	1	SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES
	Summit Materials, Inc. (“Summit Inc.”) (together with its subsidiaries, the “Company”) is a vertically-integrated construction materials company. Through its subsidiaries, it 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, a cement plant, 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 Inc. was formed as a Delaware corporation on September 23, 2014 to be a holding company. Its sole 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 initial public offering (“IPO”), 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. Certain investment funds affiliated with Blackstone Capital Partners V L.P. and Silverhawk Summit, L.P. (collectively, the “Sponsors”), as well as Summit Inc., are the primary owners of Summit Holdings.
	Initial Public Offering—Summit Inc. commenced operations on March 11, 2015 upon the pricing of the IPO of its Class A common stock. Summit Inc. raised $433.0 million, net of underwriting discounts, through the issuance of 25,555,555 shares of Class A common stock at a public offering price of $18.00 per share. Summit Inc. used the offering proceeds to purchase a number of newly-issued LP Units from Summit Holdings equal to the number of shares of Class A common stock issued to the public. Summit Inc. caused Summit Holdings to use these proceeds (i) to redeem $288.2 million in aggregate principal amount of outstanding 10 1⁄2% Senior Notes due January 31, 2020 (“Senior Notes”) at a redemption price of 100% and an applicable premium thereon; (ii) to purchase 71,428,571 Class B Units of Continental Cement Company, L.L.C. (“Continental Cement”); (iii) to pay a one-time termination fee of $13.8 million primarily to affiliates of the Sponsors in connection with the termination of a transaction and management fee agreement; and (iv) for general corporate purposes. The $288.2 million redemption of Senior Notes was completed in the second quarter of 2015 at a redemption price equal to par plus an applicable premium of $38.2 million plus $5.2 million of accrued and unpaid interest.
	Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements of Summit Holdings and the notes thereto as of and for the year ended December 27, 2014 included in Summit Inc.’s prospectus filed with the SEC on March 13, 2015. The Company’s financial position as of December 27, 2014 and the results of operations and cash flows for the three months ended March 28, 2015 have been recast to reflect those of Summit Holdings. The Company continues to follow the accounting policies set forth in those consolidated financial statements. 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 March 28, 2015 and the results of operations and cash flows for the three months ended March 28, 2015 and March 29, 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, 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%.
	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—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. Management adjusts such estimates and assumptions when circumstances dictate. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.
	Business and Credit Concentrations—The Company’s operations are conducted primarily across 17 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Kansas, Kentucky, Utah and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that any significant concentrations of credit exist with respect to individual customers or groups of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three months ended March 28, 2015 or March 29, 2014.
	Earnings per Share—The Company computes basic earnings per share attributable to stockholders by dividing income attributable to Summit Inc. by the weighted-average Class A common shares outstanding. Diluted earnings per share reflects the potential dilution beyond shares for basic earnings per share that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in the Company’s earnings. Since the Class B common shares have no economic value, they are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the Class A common shares are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic or diluted earnings per share.
	Fair Value Measurements—Certain acquisitions made by the Company require the payment of contingent amounts of purchase consideration. These payments are contingent on specified operating results being achieved in periods subsequent to the acquisition and will only be made if earn-out thresholds are achieved. Contingent consideration obligations are measured at fair value each reporting period. Any adjustments to fair value are recognized in earnings in the period identified. Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition-related liabilities:
	Contingent consideration		$	4,187	$	5,379
	The fair value of the contingent consideration obligations approximated their carrying value as of March 28, 2015 and December 27, 2014. The fair values are 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. There were no material valuation adjustments to contingent consideration obligations in the three months ended March 28, 2015 or March 29, 2014.
	Financial Instruments—The Company’s financial instruments include debt and certain acquisition-related liabilities (deferred consideration and noncompete obligations). The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			21,076		21,076		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			40,058		40,058		37,357		37,357
		-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
		-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 value 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 — On March 17, 2015, upon the consummation of the IPO and the transactions contemplated by a contribution and purchase agreement entered into with the holders of all of the outstanding Class B Units of Continental Cement, Continental Cement became a wholly-owned indirect subsidiary of Summit Holdings. The noncontrolling interests of Continental Cement were acquired for aggregate consideration of $64.1 million, consisting of $35.0 million of cash, 1,029,183 of Class A common shares and $15.0 million aggregate principal amount of non-interest bearing notes payable in six annual installments of $2.5 million, beginning on March 17, 2016.
	New Accounting Standards — In April 2015, the FASB issued a new accounting standard to simplify the presentation of debt issuance costs. Accounting Standards Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity will present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. The ASU is effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance will be applied retrospectively to all prior periods (i.e., the balance sheet for each period will be adjusted). Had the Company adopted this guidance as of the current period, both Other Assets (noncurrent) and Long-term Debt as of March 28, 2015 and December 27, 2014, would have decreased by $19.6 million and $17.2 million, respectively.
	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, which gives an employer whose fiscal year-end does not coincide with a calendar month-end (e.g., an entity that has a 52- or 53-week fiscal year) the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month-end that is closest to its fiscal year-end. The ASU is effective for public business entities for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early application is permitted, and the ASU should be applied prospectively. The Company does not expect the adoption of the ASU to have a material effect on its financial position or results of operations.
	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, prescribes a five-step model for revenue recognition that will replace most existing revenue recognition guidance in U.S. GAAP. The ASU will supersede nearly all existing revenue recognition guidance under U.S. GAAP and provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and 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 and will become effective for the Company in the first quarter of 2017. Early adoption is prohibited. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements.
	Reclassifications — Certain amounts in the prior year have been reclassified to conform to the presentation in the consolidated financial statements as of and for the quarter ended March 28, 2015.
Summit Materials, LLC [Member]
Summary of Organization and Significant Accounting Policies	1	SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES
	Summit Materials, LLC (“Summit LLC”) is a vertically integrated, heavy-side construction materials company. Through its subsidiaries, it is engaged in the production and sale of aggregates, cement, ready-mixed concrete, asphalt paving mix and concrete products. Summit LLC, through its subsidiaries (collectively, the “Company”), owns and operates quarries, sand and gravel pits, a cement plant, 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 major indirect owners are certain investment funds affiliated with Blackstone Capital Partners V L.P. and Silverhawk Summit, L.P. and Summit Materials, Inc. (“Summit Inc.”). Summit Inc. was formed as a Delaware corporation on September 23, 2014 to be a holding company. Its sole 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 (“IPO”), Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries, including Summit LLC, and, through Summit Holdings, conducts its business.
	Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto as of and for the year ended December 27, 2014 . The Company continues to follow the accounting policies set forth in those consolidated financial statements. 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 March 28, 2015 and the results of operations and cash flows for the three months ended March 28, 2015 and March 29, 2014.
	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 wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. 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 Company, L.L.C. (“Continental Cement”), a 30% redeemable ownership in Continental Cement.
	Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. Management adjusts such estimates and assumptions when circumstances dictate. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.
	Business and Credit Concentrations—The Company’s operations are conducted primarily across 17 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Kansas, Kentucky, Utah and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that any significant concentrations of credit exist with respect to individual customers or groups of customers. No single customer accounted for more than 10% of total revenue in the three months ended March 28, 2015 or March 29, 2014.
	Fair Value Measurements—Certain acquisitions made by the Company require the payment of contingent amounts of purchase consideration. These payments are contingent on specified operating results being achieved in periods subsequent to the acquisition and will only be made if earn-out thresholds are achieved. Contingent consideration obligations are measured at fair value each reporting period. Any adjustments to fair value are recognized in earnings in the period identified. Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition-related liabilities:
	Contingent consideration		$	4,187	$	5,379
	The fair value of the contingent consideration obligations approximated their carrying value as of March 28, 2015 and December 27, 2014. The fair values are 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. There were no material valuation adjustments to contingent consideration obligations in the three months ended March 28, 2015 or March 29, 2014.
	Financial Instruments—The Company’s financial instruments include debt and certain acquisition-related liabilities (deferred consideration and noncompete obligations). The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			18,576		18,576		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			31,981		31,981		37,357		37,357
		-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
		-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 value 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 — On March 17, 2015, upon the consummation of the IPO and the transactions contemplated by a contribution and purchase agreement entered into with the holders of all of the outstanding Class B Units of Continental Cement, Continental Cement became a wholly-owned indirect subsidiary of Summit LLC. The noncontrolling interests of Continental Cement were acquired for aggregate consideration of $64.1 million, consisting of $35.0 million of cash, 1,029,183 of Class A common shares and $15.0 million aggregate principal amount of non-interest bearing notes payable in six annual installments of $2.5 million, beginning on March 17, 2016. The notes payable is a liability of Summit Holdings and, is therefore excluded from the liabilities of Summit LLC.
	New Accounting Standards — In April 2015, the FASB issued a new accounting standard to simplify the presentation of debt issuance costs. Accounting Standards Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity will present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. The ASU is effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance will be applied retrospectively to all prior periods (i.e., the balance sheet for each period will be adjusted). Had the Company adopted this guidance as of the current period, both Other Assets (noncurrent) and Long-term Debt as of March 28, 2015 and December 27, 2014, would have decreased by $19.6 million and $17.2 million, respectively.
	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, which gives an employer whose fiscal year-end does not coincide with a calendar month-end (e.g., an entity that has a 52- or 53-week fiscal year) the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month-end that is closest to its fiscal year-end. The ASU is effective for public business entities for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early application is permitted, and the ASU should be applied prospectively. The Company does not expect the adoption of the ASU to have a material effect on its financial position or results of operations.
	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, prescribes a five-step model for revenue recognition that will replace most existing revenue recognition guidance in U.S. GAAP. The ASU will supersede nearly all existing revenue recognition guidance under U.S. GAAP and provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and 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 and will become effective for the Company in the first quarter of 2017. Early adoption is prohibited. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements.
	Reclassifications — Certain amounts in the prior year have been reclassified to conform to the presentation in the consolidated financial statements as of and for the quarter ended March 28, 2015.

Reorganization

Reorganization	3 Months Ended
	Mar. 28, 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 had different amounts of aggregate distributions above which its holders would share in distributions. 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 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”). In each case, the exercise price of such warrants and leverage restoration options was the IPO price of $18.00 per share. In conjunction with the Reclassification of the equity-based awards, a $14.5 million modification charge was recognized in general and administrative costs in the three months ended March 28, 2015.
	The leverage restoration options were granted under the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the “Omnibus Incentive Plan”) and are generally subject to vesting terms substantially similar to those that were applicable to the corresponding Class D interests immediately prior to the Reclassification, except that the leverage restoration options that correlate to time-vesting interests vest over four years, beginning on the Reclassification date, instead of over five years from the original grant date, and the leverage restoration options that correlate to performance-vesting interests vest only when both the relevant return multiple is achieved and a time-vesting condition is satisfied. The time-based vesting condition will be satisfied with respect to 25% of the performance-vesting options on each of the first four anniversaries of the Reclassification date. The number of leverage restoration options granted in respect of each Class D interest was based on the IPO price.
	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 did not previously hold equity-based incentive awards. These stock options have an exercise price per share of $18.00 equal to the IPO price per share 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.

Accounts_Receivable_Net

Accounts Receivable, Net	3 Months Ended
	Mar. 28, 2015
Accounts Receivable, Net	3	ACCOUNTS RECEIVABLE, NET
	Accounts receivable, net consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,			December 27,
			2015			2014
	Trade accounts receivable		$	100,528		$	131,060
	Retention receivables			10,301			12,053
	Receivables from related parties			928			333
	Accounts receivable			111,757			143,446
	Less: Allowance for doubtful accounts			(1,816	)		(2,144	)
	Accounts receivable, net		$	109,941		$	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	2	ACCOUNTS RECEIVABLE, NET
	Accounts receivable, net consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,			December 27,
			2015			2014
	Trade accounts receivable		$	100,528		$	131,060
	Retention receivables			10,301			12,053
	Receivables from related parties			928			333
	Accounts receivable			111,757			143,446
	Less: Allowance for doubtful accounts			(1,816	)		(2,144	)
	Accounts receivable, net		$	109,941		$	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	3 Months Ended
	Mar. 28, 2015
Inventories	4	INVENTORIES
	Inventories consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Aggregate stockpiles		$	90,000	$	88,211
	Finished goods			18,355		8,826
	Work in process			2,065		1,801
	Raw materials			22,887		12,715
	Total		$	133,307	$	111,553
Summit Materials, LLC [Member]
Inventories	3	INVENTORIES
	Inventories consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Aggregate stockpiles		$	90,000	$	88,211
	Finished goods			18,355		8,826
	Work in process			2,065		1,801
	Raw materials			22,887		12,715
	Total		$	133,307	$	111,553

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 28, 2015
Accrued Expenses	5	ACCRUED EXPENSES
	Accrued expenses consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Interest		$	15,917	$	32,475
	Payroll and benefits			13,100		20,326
	Capital lease obligations			17,926		17,530
	Insurance			12,469		11,402
	Non-income taxes			5,765		5,520
	Professional fees			3,051		3,299
	Other (1)			13,384		10,944
	Total		$	81,612	$	101,496
		-1	Consists primarily of subcontractor and working capital settlement accruals.
Summit Materials, LLC [Member]
Accrued Expenses	4	ACCRUED EXPENSES
	Accrued expenses consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Interest		$	15,917	$	32,475
	Payroll and benefits			13,100		20,326
	Capital lease obligations			17,926		17,530
	Insurance			12,469		11,402
	Non-income taxes			5,765		5,520
	Professional fees			3,051		3,299
	Other (1)			13,384		10,944
	Total		$	81,612	$	101,496
	-1	Consists primarily of subcontractor and working capital settlement accruals.

Debt

Debt	3 Months Ended
	Mar. 28, 2015
Debt	6	DEBT
	Debt consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,			December 27,
			2015			2014
	Long-term debt:
	$625.0 million senior notes, including a $25.2 million and $26.5 million net premium at March 28, 2015 and December 27, 2014, respectively			650,225			651,548
	$414.6 million term loan, net of $2.1 million discount at March 28, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014			412,468			413,369
	Total			1,062,693			1,064,917
	Current portion of long-term debt			5,275			5,275
	Long-term debt		$	1,057,418		$	1,059,642
	The contractual payments of long-term debt, including current maturities, for the five years subsequent to March 28, 2015, are as follows:
	2015 (nine months)		$	4,220
	2016			4,220
	2017			4,220
	2018			3,165
	2019			398,790
	2020			625,000
	Total			1,039,615
	Plus: Original issue net premium			23,078
	Total debt		$	1,062,693
	Summit Materials, LLC (“Summit LLC”) and Summit Materials Finance Corp. (“Finance Corp.” and collectively, the “Issuers”) issued $250.0 million aggregate principal amount of Senior Notes under an indenture dated January 30, 2012 (as amended and supplemented, the “Indenture”). In addition to the Senior Notes, Summit LLC has credit facilities which provide for term loans in an aggregate amount of $422.0 million and revolving credit commitments in an aggregate amount of $235.0 million (the “Senior Secured Credit Facilities”).
	On January 17, 2014 and September 8, 2014, the Issuers issued an additional $260.0 million and $115.0 million, respectively, aggregate principal amount of Senior Notes (the “Additional Notes”), receiving proceeds of $409.3 million, before payment of fees and expenses and including an aggregate $34.3 million premium. The proceeds from the sale of the Additional Notes were used for the purchases of acquisitions, to make payments on the revolving credit facility and for general corporate purposes. The Additional Notes are treated as a single series with the $250.0 million of Senior Notes (the “Existing Notes”) and have substantially the same terms as those of the Existing Notes. The Additional Notes and the Existing Notes are treated as one class under the Indenture.
	Senior Notes—Interest on the Senior Notes is payable semi-annually in arrears. The Indenture contains covenants limiting, among other things, Summit LLC and its restricted subsidiaries’ ability to incur additional indebtedness or issue certain preferred shares, pay dividends, redeem stock or make other distributions, make certain investments, sell or transfer certain assets, create liens, consolidate, merge, sell or otherwise dispose of all or substantially all of the Company’s assets, enter into certain transactions with affiliates, and designate subsidiaries as unrestricted subsidiaries. The Indenture also contains customary events of default. As of March, 28, 2015 and December 27, 2014, the Company was in compliance with all covenants.
	Senior Secured Credit Facilities—Under the Senior Secured Credit Facilities, Summit LLC has entered into term loans totaling $422.0 million with required principal repayments of 0.25% of term debt due on the last business day of each March, June, September and December. The unpaid principal balance is due in full on the maturity date, which is January 30, 2019.
	On March 11, 2015, the Company entered into Amendment No. 3 to the Credit Agreement governing the Senior Secured Credit Facilities, dated as of January 30, 2012, 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 17, 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, $0.8 million of financing fees were charged to earnings in the three months ended March 28, 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 March 28, 2015 was 4.05%.
	There were no outstanding borrowings under the revolving credit facility as of March 28, 2015, leaving remaining borrowing capacity of $211.7 million, which is net of $23.3 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 must adhere to certain financial covenants related to its debt and interest leverage ratios, as defined in the Senior Secured Credit Facilities. The consolidated first lien net leverage ratio, reported each quarter, should be no greater than 4.5:1.0. The interest coverage ratio must be at least 1.70:1.0 from January 1, 2013 through December 31, 2014 and 1.85:1.0 thereafter. As of March 27, 2015 and December 27, 2014, the Company was in compliance with all covenants. Summit LLC’s wholly-owned domestic subsidiary companies are subject to certain exclusions and exceptions are named as subsidiary guarantors of the Senior 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 the debt totaled $22.0 million and $17.2 million for the three months ended March 28, 2015 and March 29, 2014, respectively. The following table presents the activity for the deferred financing fees for the three months ended March 28, 2015 and March 29, 2014:
			Deferred financing fees
	Balance — December 27, 2014		$	17,215
	Loan origination fees			4,048
	Amortization			(982	)
	Write off of deferred financing fees			(688	)
	Balance — March 28, 2015		$	19,593
	Balance — December 28, 2013		$	11,485
	Loan origination fees			6,309
	Amortization			(850	)
	Balance — March 29, 2014		$	16,944
	Other—On January 15, 2015, the Company’s wholly-owned subsidiary in British Columbia, Canada entered into an agreement with HSBC for a (i) $6.0 million Canadian dollar (“CAD”) revolving credit commitment to be used for operating activities that bears interest per annum equal to the bank’s prime rate plus 0.20%, (ii) $0.5 million CAD revolving credit commitment to be used for capital equipment that bears interest per annum at the bank’s prime rate plus 0.90% and (iii) $0.4 million CAD revolving credit commitment to provide guarantees on behalf of Mainland. There were no amounts outstanding under this agreement as of March 28, 2015.
Summit Materials, LLC [Member]
Debt	5	DEBT
	Debt consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,			December 27,
			2015			2014
	Long-term debt:
	$625.0 million senior notes, including a $25.2 million and $26.5 million net premium at March 28, 2015 and December 27, 2014, respectively			650,225			651,548
	$414.6 million term loan, net of $2.1 million discount at March 28, 2015 and
	$415.7 million term loan, net of $2.3 million discount at December 27, 2014			412,468			413,369
	Total			1,062,693			1,064,917
	Current portion of long-term debt			5,275			5,275
	Long-term debt		$	1,057,418		$	1,059,642
	The contractual payments of long-term debt, including current maturities, for the five years subsequent to March 28, 2015, are as follows:
	2015 (nine months)		$	4,220
	2016			4,220
	2017			4,220
	2018			3,165
	2019			398,790
	2020			625,000
	Total			1,039,615
	Plus: Original issue net premium			23,078
	Total debt		$	1,062,693
	Summit LLC and Summit Materials Finance Corp.(“Finance Corp.” and collectively, the “Issuers”) issued $250.0 million aggregate principal amount of Senior Notes under an indenture dated January 30, 2012 (as amended and supplemented, the “Indenture”). In addition to the Senior Notes, Summit LLC has credit facilities which provide for term loans in an aggregate amount of $422.0 million and revolving credit commitments in an aggregate amount of $235.0 million (the “Senior Secured Credit Facilities”).
	On January 17, 2014 and September 8, 2014, the Issuers issued an additional $260.0 million and $115.0 million, respectively, aggregate principal amount of Senior Notes (the “Additional Notes”), receiving proceeds of $409.3 million, before payment of fees and expenses and including an aggregate $34.3 million premium. The proceeds from the sale of the Additional Notes were used for the purchases of acquisitions, to make payments on the revolving credit facility and for general corporate purposes. The Additional Notes are treated as a single series with the $250.0 million of Senior Notes (the “Existing Notes”) and have substantially the same terms as those of the Existing Notes. The Additional Notes and the Existing Notes are treated as one class under the Indenture.
	Senior Notes—Interest on the Senior Notes is payable semi-annually in arrears. The Indenture contains covenants limiting, among other things, Summit LLC and its restricted subsidiaries’ ability to incur additional indebtedness or issue certain preferred shares, pay dividends, redeem stock or make other distributions, make certain investments, sell or transfer certain assets, create liens, consolidate, merge, sell or otherwise dispose of all or substantially all of the Company’s assets, enter into certain transactions with affiliates, and designate subsidiaries as unrestricted subsidiaries. The Indenture also contains customary events of default. As of March, 28, 2015 and December 27, 2014, the Company was in compliance with all covenants.
	Senior Secured Credit Facilities—Under the Senior Secured Credit Facilities, Summit LLC has entered into term loans totaling $422.0 million with required principal repayments of 0.25% of term debt due on the last business day of each March, June, September and December. The unpaid principal balance is due in full on the maturity date, which is January 30, 2019.
	On March 11, 2015, the Company entered into Amendment No. 3 to the Credit Agreement governing the Senior Secured Credit Facilities, dated as of January 30, 2012, 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 17, 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, $0.8 million of financing fees were charged to earnings in the three months ended March 28, 2015.
	The revolving credit facility bears interest per annum equal to, at Summit Material’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 March 28, 2015 was 4.05%.
	There were no outstanding borrowings under the revolving credit facility as of March 28, 2015, leaving remaining borrowing capacity of $211.7 million, which is net of $23.3 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 must adhere to certain financial covenants related to its debt and interest leverage ratios, as defined in the Senior Secured Credit Facilities. The consolidated first lien net leverage ratio, reported each quarter, should be no greater than 4.5:1.0. The interest coverage ratio must be at least 1.70:1.0 from January 1, 2013 through December 31, 2014 and 1.85:1.0 thereafter. As of March 27, 2015 and December 27, 2014, the Company was in compliance with all covenants. Summit LLC’s wholly-owned domestic subsidiary companies are subject to certain exclusions and exceptions are named as subsidiary guarantors of the Senior 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 the debt totaled $22.0 million and $17.2 million for the three months ended March 28, 2015 and March 29, 2014, respectively. The following table presents the activity for the deferred financing fees for the three months ended March 28, 2015 and March 29, 2014:
			Deferred financing fees
	Balance — December 27, 2014		$	17,215
	Loan origination fees			4,048
	Amortization			(982	)
	Write off of deferred financing fees			(688	)
	Balance — March 28, 2015		$	19,593
	Balance — December 28, 2013		$	11,485
	Loan origination fees			6,309
	Amortization			(850	)
	Balance — March 29, 2014		$	16,944
	Other—On January 15, 2015, the Company’s wholly-owned subsidiary in British Columbia, Canada entered into an agreement with HSBC for a (i) $6.0 million Canadian dollar (“CAD”) revolving credit commitment to be used for operating activities that bears interest per annum equal to the bank’s prime rate plus 0.20%, (ii) $0.5 million CAD revolving credit commitment to be used for capital equipment that bears interest per annum at the bank’s prime rate plus 0.90% and (iii) $0.4 million CAD revolving credit commitment to provide guarantees on behalf of Mainland. There were no amounts outstanding under this agreement as of March 28, 2015.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 28, 2015
Income Taxes	7	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 Corporations are reflected in the Company’s accounts.
	As of March 28, 2015 and December 27, 2014, Summit Inc. and subsidiaries have 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 for the three months ended March 28, 2015 and March 29, 2014.
	Summit Inc. — Due to the timing of the IPO, taxes were calculated based on activity from March 12, 2015 through the end of the first quarter. Summit Inc.’s net deferred tax asset as of March 28, 2015 of $50.5 million, which is offset by a full valuation allowance, primarily consists of a $69.0 million temporary difference related to the tax intangible assets basis in excess of book, offset by the $6.9 million and $10.9 million book aggregate reserves and fixed assets in excess of tax basis, respectively.
	In assessing the realizability of deferred tax assets as of March 28, 2015, management considered whether it was more likely than not that the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible, projected future taxable income and tax-planning strategies. After considering these factors, management concluded that the deferred tax asset realization did not meet the more likely than not requirement and a full valuation allowance is recorded against the Summit Inc. net deferred tax assets as of the end of the first quarter.
	For interim income tax reporting, management estimates its annual effective tax rate and applies it to the year to date profit (loss) from continuing operations before taxes. Tax jurisdictions with a projected or year to date loss for which a tax benefit cannot be realized are excluded from this calculation; therefore, there is no provision for income taxes related to the limited liability companies that are passed on to Summit Inc. for the three months ended March 28, 2015.
	C Corporation Subsidiaries—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.
	Tax Receivable Agreement—Upon the consummation of the Reorganization, the Company entered into a tax receivable agreement with the holders of LP Units and certain other indirect pre-IPO owners (“Investor Entities”) that provides for the payment by Summit Inc. to exchanging holders of LP Units of 85% of the benefits, if any, that Summit Inc. is deemed to realize as a result of (i) increases in tax basis of the tangible and intangible assets of Summit Holdings resulting from future exchanges of LP Units for shares of Class A common stock and (ii) the utilization of certain net operating losses of the Investor Entities and certain other tax benefits related to entering into the tax receivable agreement, including tax benefits attributable to payments under the tax receivable agreement. As of March 28, 2015, no LP units had been exchanged.
Summit Materials, LLC [Member]
Income Taxes	7	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 March 28, 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 for the three or nine months ended March 28, 2015 and March 29, 2014.

Net_Loss_Per_Share

Net Loss Per Share	3 Months Ended
	Mar. 28, 2015
Net Loss Per Share	8	NET LOSS 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. The outstanding warrants and stock options granted in connection with the IPO are excluded from the calculations below as they would have an antidilutive effect as the Company had a net loss during the period. The number of antidilutive shares was 1,746,210 for the three months ended March 28, 2015.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 28, 2015
Commitments and Contingencies	9	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’s policy is to record legal fees as incurred.
	Litigation and Claims—The Company is obligated under an indemnification agreement entered into with the sellers of Harper Contracting, Inc., Harper Sand and Gravel, Inc., Harper Excavating, Inc., Harper Ready Mix Company, Inc. and Harper Investments, Inc. (collectively, “Harper”) for the sellers’ 40% ownership interests in a joint venture agreement. The Company has the rights to any benefits under the joint venture as well as the assumption of any obligations, but does not own equity interests in the joint venture. The joint venture incurred significant losses on a highway project in Utah, which resulted in requests for funding from the joint venture partners and, ultimately, from the Company. Through March 28, 2015, the Company has funded $8.8 million, of which $4.0 million was funded in 2012 and $4.8 million was funded in 2011. On April 2, 2015, the Utah Department of Transportation filed suit in the Fourth District Court of Utah County, Utah against the joint venture and the parties to the joint venture seeking damages of at least $29.4 million. As of March 28, 2015 and December 27, 2014, an accrual of $4.3 million was recorded in other noncurrent liabilities as management’s best estimate of loss related to this matter.
	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. As of March 28, 2015 and December 27, 2014, the company had $3.9 million of unapproved change orders and claims ($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).
	Environmental Remediation—The Company’s operations are subject to and affected by federal, state, provincial and local laws and regulations relating to the environment, health and safety and other regulatory matters. These operations require environmental operating permits, which are subject to modification, renewal and revocation. The Company regularly monitors and reviews its operations, procedures and policies for compliance with these laws and regulations. Despite these compliance efforts, risk of environmental liability is inherent in the operation of the Company’s business, as it is with other companies engaged in similar businesses, and there can be no assurance that environmental liabilities or noncompliance will not have a material adverse effect on the Company’s consolidated financial position, results of operations or liquidity in the future.
	Other — In the ordinary course of business, the Company enters into various firm purchase commitments for certain raw materials and services. The terms of the purchase commitments are generally less than one year. Management does not expect any significant changes in the market value of these goods and services during the commitment period that would have a material adverse effect on the financial position, results of operations or liquidity of the Company.
Summit Materials, LLC [Member]
Commitments and Contingencies	8	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’s policy is to record legal fees as incurred.
	Litigation and Claims—The Company is obligated under an indemnification agreement entered into with the sellers of Harper Contracting, Inc., Harper Sand and Gravel, Inc., Harper Excavating, Inc., Harper Ready Mix Company, Inc. and Harper Investments, Inc. (collectively, “Harper”) for the sellers’ 40% ownership interests in a joint venture agreement. The Company has the rights to any benefits under the joint venture as well as the assumption of any obligations, but does not own equity interests in the joint venture. The joint venture incurred significant losses on a highway project in Utah, which resulted in requests for funding from the joint venture partners and, ultimately, from the Company. Through March 28, 2015, the Company has funded $8.8 million, of which $4.0 million was funded in 2012 and $4.8 million was funded in 2011. On April 2, 2015, the Utah Department of Transportation filed suit in the Fourth District Court of Utah County, Utah against the joint venture and the parties to the joint venture seeking damages of at least $29.4 million. As of March 28, 2015 and December 27, 2014, an accrual of $4.3 million was recorded in other noncurrent liabilities as management’s best estimate of loss related to this matter.
	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. As of March 28, 2015 and December 27, 2014, the company had $3.9 million of unapproved change orders and claims ($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).
	Environmental Remediation—The Company’s operations are subject to and affected by federal, state, provincial and local laws and regulations relating to the environment, health and safety and other regulatory matters. These operations require environmental operating permits, which are subject to modification, renewal and revocation. The Company regularly monitors and reviews its operations, procedures and policies for compliance with these laws and regulations. Despite these compliance efforts, risk of environmental liability is inherent in the operation of the Company’s business, as it is with other companies engaged in similar businesses, and there can be no assurance that environmental liabilities or noncompliance will not have a material adverse effect on the Company’s consolidated financial position, results of operations or liquidity in the future.
	Other—In the ordinary course of business, the Company enters into various firm purchase commitments for certain raw materials and services. The terms of the purchase commitments are generally less than one year. Management does not expect any significant changes in the market value of these goods and services during the commitment period that would have a material adverse effect on the financial position, results of operations or liquidity of the Company.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	3 Months Ended
	Mar. 28, 2015
Supplemental Cash Flow Information	10	SUPPLEMENTAL CASH FLOW INFORMATION
	Supplemental cash flow information is as follows:
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash payments:
	Interest		$	39,165		$	19,970
	Income taxes			453			795
	Non cash financing activities:
	Purchase of noncontrolling interest in Continental Cement		$	(29,102	)	$	—
Summit Materials, LLC [Member]
Supplemental Cash Flow Information	9	SUPPLEMENTAL CASH FLOW INFORMATION
	Supplemental cash flow information is as follows:
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash payments:
	Interest		$	39,165		$	19,970
	Income taxes			453			795
	Non cash financing activities:
	Purchase of noncontrolling interest in Continental Cement		$	(64,102	)	$	—

Segment_Information

Segment Information	3 Months Ended
	Mar. 28, 2015
Segment Information	11	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
			March 28,			March 29,
			2015			2014
	Revenue:
	West region		$	127,674		$	94,894
	Central region			56,609			47,542
	East region			9,704			8,655
	Total revenue		$	193,987		$	151,091
			Three months ended
			March 28,			March 29,
			2015			2014
	Adjusted EBITDA
	West region		$	11,869		$	1,791
	Central region			710			(423	)
	East region			(7,867	)		(9,338	)
	Corporate and other			(9,687	)		(7,499	)
	Total reportable segments and corporate			(4,975	)		(15,469	)
	Interest expense			24,109			18,819
	Depreciation, depletion, amortization and accretion			26,126			19,356
	Initial public offering costs			28,296			—
	Loss on debt financings			799			—
	Loss from continuing operations before taxes		$	(84,305	)	$	(53,644	)
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash paid for capital expenditures:
	West region		$	5,419		$	4,138
	Central region			8,624			12,401
	East region			2,774			2,245
	Total reportable segments			16,817			18,784
	Corporate and other			891			1,157
	Total capital expenditures		$	17,708		$	19,941
			Three months ended
			March 28,			March 29,
			2015			2014
	Depreciation, depletion, amortization and accretion:
	West region		$	12,088		$	6,747
	Central region			10,072			8,847
	East region			3,477			3,457
	Total reportable segments			25,637			19,051
	Corporate and other			489			305
	Total depreciation, depletion, amortization and accretion		$	26,126		$	19,356
			March 28,			December 27,
			2015			2014
	Total assets:
	West region		$	760,881		$	777,981
	Central region			704,314			704,134
	East region			219,607			221,598
	Total reportable segments			1,684,802			1,703,713
	Corporate and other			333,452			26,064
	Total		$	2,018,254		$	1,729,777
			Three months ended
			March 28,			March 29,
			2015			2014
	Revenue by product:*
	Aggregates		$	52,337		$	31,550
	Cement			11,819			7,707
	Ready-mixed concrete			70,088			42,380
	Asphalt			20,914			24,396
	Paving and related services			43,899			55,857
	Other			(5,070	)		(10,799	)
	Total revenue		$	193,987		$	151,091
	*	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	10	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
			March 28,			March 29,
			2015			2014
	Revenue:
	West region		$	127,674		$	94,894
	Central region			56,609			47,542
	East region			9,704			8,655
	Total revenue		$	193,987		$	151,091
			Three months ended
			March 28,			March 29,
			2015			2014
	Adjusted EBITDA
	West region		$	11,869		$	1,791
	Central region			710			(423	)
	East region			(7,867	)		(9,338	)
	Corporate and other			(9,687	)		(7,499	)
	Total reportable segments and corporate			(4,975	)		(15,469	)
	Interest expense			24,109			18,819
	Depreciation, depletion, amortization and accretion			26,126			19,356
	Initial public offering costs			28,296			—
	Loss on debt financings			799			—
	Loss from continuing operations before taxes		$	(84,305	)	$	(53,644	)
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash paid for capital expenditures:
	West region		$	5,419		$	4,138
	Central region			8,624			12,401
	East region			2,774			2,245
	Total reportable segments			16,817			18,784
	Corporate and other			891			1,157
	Total capital expenditures		$	17,708		$	19,941
			Three months ended
			March 28,			March 29,
			2015			2014
	Depreciation, depletion, amortization and accretion:
	West region		$	12,088		$	6,747
	Central region			10,072			8,847
	East region			3,477			3,457
	Total reportable segments			25,637			19,051
	Corporate and other			489			305
	Total depreciation, depletion, amortization and accretion		$	26,126		$	19,356
			March 28,			December 27,
			2015			2014
	Total assets:
	West region		$	760,881		$	777,981
	Central region			704,314			704,134
	East region			219,607			221,598
	Total reportable segments			1,684,802			1,703,713
	Corporate and other			333,452			26,064
	Total		$	2,018,254		$	1,729,777
			Three months ended
			March 28,			March 29,
			2015			2014
	Revenue by product:*
	Aggregates		$	52,337		$	31,550
	Cement			11,819			7,707
	Ready-mixed concrete			70,088			42,380
	Asphalt			20,914			24,396
	Paving and related services			43,899			55,857
	Other			(5,070	)		(10,799	)
	Total revenue		$	193,987		$	151,091
*	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	3 Months Ended
	Mar. 28, 2015
Related Party Transactions	12	RELATED PARTY TRANSACTIONS
	Under the terms of an agreement with Summit Holdings and Blackstone Management Partners (“BMP”), whose affiliates include controlling stockholders of the Company, BMP provided monitoring, advisory and consulting services to the Company through March 17, 2015. In consideration for these services, the Company paid BMP the greater of $300,000 or 2.0% of the Company’s annual consolidated profit, as defined in the agreement. The management fees paid pursuant to this agreement are included in general and administrative expenses. The Company incurred management fees due to BMP totaling $1.0 million and $0.9 million during the period between December 28, 2014 and March 17, 2015 and in the three months ended March 29, 2014, respectively.
	In connection with the IPO, the transaction and management fee agreement with BMP was terminated on March 17, 2015 for total fees of approximately $13.8 million, $13.4 million of which was paid to affiliates of Blackstone and the remaining $0.4 million was paid to affiliates of Silverhawk Summit, L.P. and to certain other equity investors.
	BMP also 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. Under the terms of the agreement, BMP was permitted to assign, and had assigned, a portion of the fees to which it is entitled to Silverhawk Summit, L.P. and to certain other equity investors. During the three months ended March 28, 2015 and March 29, 2014, the Company paid BMP $1.7 million under this agreement and 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 addition to the fees paid to BMP pursuant to the agreements described above, the Company reimbursed BMP for direct expenses incurred, which were not material in the three months ended March 28, 2015 and March 29, 2014.
	Blackstone Advisory Partners L.P., an affiliate of Blackstone, served as an initial purchaser of $13.0 million and $5.75 million principal amount of the senior notes issued in January 2014 and September 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 and $1.7 million during the period between December 28, 2014 and March 11, 2015 and in the three months ended March 29, 2014, respectively. Accounts receivables due from the former noncontrolling member were $0.2 million as of December 27, 2014. In addition, in the first quarter of 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 three months ended March 29, 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	11	RELATED PARTY TRANSACTIONS
	Under the terms of an agreement with Summit Holdings and Blackstone Management Partners (“BMP”), whose affiliates are controlling owners of the Company, BMP provided monitoring, advisory and consulting services to the Company through March 17, 2015. In consideration for these services, the Company paid BMP the greater of $300,000 or 2.0% of the Company’s annual consolidated profit, as defined in the agreement. The management fees paid pursuant to this agreement are included in general and administrative expenses. The Company incurred management fees due to BMP totaling $1.0 million and $0.9 million during the period between December 28, 2014 and March 17, 2015 and in the three months ended March 29, 2014, respectively.
	In connection with the IPO, the transaction and management fee agreement with BMP was terminated on March 17, 2015 for total fees of approximately $13.8 million, $13.4 million of which was paid to affiliates of Blackstone and the remaining $0.4 million was paid to affiliates of Silverhawk Summit, L.P. and to certain other equity investors.
	BMP also 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. Under the terms of the agreement, BMP was permitted to assign, and had assigned, a portion of the fees to which it is entitled to Silverhawk Summit, L.P. and to certain other equity investors. During the three months ended March 29, 2014, the Company paid BMP $1.7 million under this agreement and 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 addition to the fees paid to BMP pursuant to the agreements described above, the Company reimbursed BMP for direct expenses incurred, which were not material in the three months ended March 28, 2015 and March 29, 2014.
	Blackstone Advisory Partners L.P., an affiliate of Blackstone, served as an initial purchaser of $13.0 million and $5.75 million principal amount of the senior notes issued in January 2014 and September 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 and $1.7 million during the period between December 28, 2014 and March 11, 2015 and in the three months ended March 29, 2014, respectively. Accounts receivables due from the former noncontrolling member were immaterial as of December 27, 2014. In addition, in the first quarter of 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 three months ended March 29, 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.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 28, 2015
Subsequent Events	13	SUBSEQUENT EVENTS
	On April 16, 2015, Continental Cement, Summit LLC, Summit Holdings and Lafarge North America Inc. (“Lafarge”) entered into an Asset Purchase Agreement (the “Davenport Purchase Agreement”). If the conditions in the Davenport Purchase Agreement are met and the parties proceed to closing, at closing, the Company will acquire certain assets (the “Davenport Assets”) from Lafarge, including a cement plant, a quarry and seven cement distribution terminals (the “Davenport Acquisition”).
	The Davenport Purchase Agreement contains customary representations, warranties, covenants, and termination rights. The consummation of the Davenport Acquisition is subject to customary conditions, including absence of a material adverse effect on the Davenport Assets. The consummation of the Davenport Acquisition is also subject to the conditions that (i) the Federal Trade Commission shall have accepted for public comment an Agreement Containing Order that, if issued as a final order, would require Lafarge to divest the Transferred Business (as defined in the Davenport Purchase Agreement) to Continental Cement, (ii) the merger of Lafarge’s parent company, Lafarge S.A., with Holcim Ltd. shall have been consummated, and (iii) the conditions in the Bettendorf Purchase Agreement (as defined below) shall have been satisfied or waived. The aggregate purchase price for the Davenport Acquisition is expected to be approximately $450 million in cash, subject to certain adjustments as set forth in the Davenport Purchase Agreement, plus the Bettendorf Assets (as defined below). The Company expects to fund the purchase price with debt issued by Summit LLC and equity issued by Summit Inc. The transaction is expected to close in the third quarter of 2015. There can be no assurance that the Davenport Acquisition will be completed in the anticipated time frame, or at all.
	In connection with the entry into the Davenport Agreement, Continental Cement, Summit LLC, Summit Holdings and Lafarge entered into an Asset Purchase Agreement (the “Bettendorf Purchase Agreement”). If the conditions in the Bettendorf Purchase Agreement are met and the parties proceed to closing, at closing, Continental Cement will convey certain assets to Lafarge, including a cement distribution terminal (the “Bettendorf Assets”) as partial consideration for the sale of the Davenport Assets pursuant to the Davenport Purchase Agreement (the “Bettendorf Acquisition”).
Summit Materials, LLC [Member]
Subsequent Events	13	SUBSEQUENT EVENTS
	On April 16, 2015, Continental Cement, Summit LLC, Summit Holdings and Lafarge North America Inc. (“Lafarge”) entered into an Asset Purchase Agreement (the “Davenport Purchase Agreement”). If the conditions in the Davenport Purchase Agreement are met and the parties proceed to closing, at closing, the Company will acquire certain assets (the “Davenport Assets”) from Lafarge, including a cement plant, a quarry and seven cement distribution terminals (the “Davenport Acquisition”).
	The Davenport Purchase Agreement contains customary representations, warranties, covenants, and termination rights. The consummation of the Davenport Acquisition is subject to customary conditions, including absence of a material adverse effect on the Davenport Assets. The consummation of the Davenport Acquisition is also subject to the conditions that (i) the Federal Trade Commission shall have accepted for public comment an Agreement Containing Order that, if issued as a final order, would require Lafarge to divest the Transferred Business (as defined in the Davenport Purchase Agreement) to Continental Cement, (ii) the merger of Lafarge’s parent company, Lafarge S.A., with Holcim Ltd. shall have been consummated, and (iii) the conditions in the Bettendorf Purchase Agreement (as defined below) shall have been satisfied or waived. The aggregate purchase price for the Davenport Acquisition is expected to be approximately $450 million in cash, subject to certain adjustments as set forth in the Davenport Purchase Agreement, plus the Bettendorf Assets (as defined below). The Company expects to fund the purchase price with debt issued by Summit LLC and equity issued by Summit Inc. The transaction is expected to close in the third quarter of 2015. There can be no assurance that the Davenport Acquisition will be completed in the anticipated time frame, or at all.
	In connection with the entry into the Davenport Agreement, Continental Cement, Summit LLC, Summit Holdings and Lafarge entered into an Asset Purchase Agreement (the “Bettendorf Purchase Agreement”). If the conditions in the Bettendorf Purchase Agreement are met and the parties proceed to closing, at closing, Continental Cement will convey certain assets to Lafarge, including a cement distribution terminal (the “Bettendorf Assets”) as partial consideration for the sale of the Davenport Assets pursuant to the Davenport Purchase Agreement (the “Bettendorf Acquisition”).
	In April 2015, the Issuers redeemed $288.2 million aggregate principal amount of their outstanding Senior Notes at a redemption price equal to par plus an applicable premium of $38.2 million plus $5.2 million of accrued and unpaid interest.

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE LOSS (Summit Materials, LLC [Member])	3 Months Ended
	Mar. 28, 2015
Summit Materials, LLC [Member]
ACCUMULATED OTHER COMPREHENSIVE LOSS	6	ACCUMULATED OTHER COMPREHENSIVE LOSS
	The changes in each component of accumulated other comprehensive loss consisted of the following:
			Pension and			Foreign currency			Accumulated
			Post-			translation			other
			retirement plans			adjustments			comprehensive
									loss
	Balance — December 27, 2014		$	(9,730	)	$	(5,816	)	$	(15,546	)
	Foreign currency translation adjustment			—			(6,299	)		(6,299	)
	Balance — March 28, 2015		$	(9,730	)	$	(12,115	)	$	(21,845	)
	Balance — December 28, 2013		$	(6,045	)	$	—		$	(6,045	)
	Postretirement curtailment adjustment			(942	)		—			(942	)
	Postretirement liability adjustment			1,515			—			1,515
	Balance — March 29, 2014		$	(5,472	)	$	—		$	(5,472	)

SENIOR_NOTES_GUARANTOR_AND_NON

SENIOR NOTES' GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Summit Materials, LLC [Member])	3 Months Ended
	Mar. 28, 2015
Summit Materials, LLC [Member]
SENIOR NOTES' GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION	12	SENIOR NOTES’ GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION
	Summit LLC’s domestic wholly-owned subsidiary companies other than Finance Corp. (the “Guarantors”) are named as guarantors (collectively, the “Guarantors”) of 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 months ended March 28, 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
	March 28, 2015
			Issuers			Wholly-			Non-			Eliminations			Consolidated
						owned			Guarantors
						Guarantors
	Assets
	Current assets:
	Cash		$	314,635		$	577		$	7,895		$	(8,127	)	$	314,980
	Accounts receivable, net			—			101,089			9,269			(417	)		109,941
	Intercompany receivables			367,129			19,372			5,727			(392,228	)		—
	Cost and estimated earnings in excess of billings			—			11,581			255			—			11,836
	Inventories			—			125,725			7,582			—			133,307
	Other current assets			739			15,485			1,252			—			17,476
	Total current assets			682,503			273,829			31,980			(400,772	)		587,540
	Property, plant and equipment, net			7,436			912,608			28,085			—			948,129
	Goodwill			—			364,309			51,273			—			415,582
	Intangible assets, net			—			14,547			2,344			—			16,891
	Other assets			1,308,994			137,950			1,298			(1,398,130	)		50,112
	Total assets		$	1,998,933		$	1,703,243		$	114,980		$	(1,798,902	)	$	2,018,254
	Liabilities, Redeemable Noncontrolling Interest and Member’s Interest
	Current liabilities:
	Current portion of debt		$	5,275		$	5,266		$	—		$	(5,266	)	$	5,275
	Current portion of acquisition-related liabilities			—			22,351			—			—			22,351
	Accounts payable			5,073			61,530			4,654			(417	)		70,840
	Accrued expenses			25,083			60,750			3,906			(8,127	)		81,612
	Intercompany payables			109,863			278,938			3,427			(392,228	)		—
	Billings in excess of costs and estimated earnings			—			8,309			—			—			8,309
	Total current liabilities			145,294			437,144			11,987			(406,038	)		188,387
	Long-term debt			1,057,418			632,861			—			(632,861	)		1,057,418
	Acquisition-related liabilities			—			36,168			—			—			36,168
	Other noncurrent liabilities			751			94,243			57,546			(55,107	)		97,433
	Total liabilities			1,203,463			1,200,416			69,533			(1,094,006	)		1,379,406
	Total stockholders’ equity/partners’ interest			795,470			502,827			45,447			(704,896	)		638,848
	Total liabilities, redeemable noncontrolling interest and member’s interest		$	1,998,933		$	1,703,243		$	114,980		$	(1,798,902	)	$	2,018,254
	Condensed Consolidating Balance Sheets
	December 27, 2014
			Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
						Guarantor			owned			Guarantors
									Guarantors
	Assets
	Current assets:
	Cash		$	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 March 28, 2015
		Issuers			Wholly-			Non-			Eliminations			Consolidated
					owned			Guarantors
					Guarantors
Revenue		$	—		$	179,343		$	33,646		$	(19,002	)	$	193,987
Cost of revenue (excluding items shown separately below)			—			151,226			26,045			(19,002	)		158,269
General and administrative expenses			37,781			29,151			1,666			—			68,598
Depreciation, depletion, amortization and accretion			490			24,153			1,483			—			26,126
Operating (loss) income			(38,271	)		(25,187	)		4,452			—			(59,006	)
Other (income) expense, net			25,786			739			149			(25,484	)		1,190
Interest expense			13,798			16,055			881			(6,625	)		24,109
Income from continuing operations before taxes			(77,855	)		(41,981	)		3,422			32,109			(84,305	)
Income tax benefit (expense)			—			(4,538	)		70			—			(4,468	)
Income from continuing operations			(77,855	)		(37,443	)		3,352			32,109			(79,837	)
Income from discontinued operations			—			—			—			—			—
Net income			(77,855	)		(37,443	)		3,352			32,109			(79,837	)
Net income attributable to minority interest			—			—			—			(1,982	)		(1,982	)
Net income attributable to member of Summit Materials, LLC		$	(77,855	)	$	(37,443	)	$	3,352		$	34,091		$	(77,855	)
Comprehensive income attributable to member of Summit Materials, LLC		$	(84,154	)	$	(37,443	)	$	(2,947	)	$	40,390		$	(84,154	)
Condensed Consolidating Statements of Operations
For the three months ended March 29, 2014
		Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
					Guarantor			owned			Guarantors
								Guarantors
Revenue		$	—		$	7,707		$	140,410		$	6,332		$	(3,358	)	$	151,091
Cost of revenue (excluding items shown separately below)			—			10,903			117,624			3,506			(3,358	)		128,675
General and administrative expenses			7,688			1,674			28,441			276			—			38,079
Depreciation, depletion, amortization and accretion			304			3,074			15,712			266			—			19,356
Operating (loss) income			(7,992	)		(7,944	)		(21,367	)		2,284			—			(35,019	)
Other expense (income), net			36,825			(97	)		(195	)		49			(36,776	)		(194	)
Interest expense			5,736			2,846			11,772			26			(1,561	)		18,819
(Loss) income from continuing operations before taxes			(50,553	)		(10,693	)		(32,944	)		2,209			38,337			(53,644	)
Income tax benefit			—			—			(596	)		—			—			(596	)
(Loss) income from continuing operations			(50,553	)		(10,693	)		(32,348	)		2,209			38,337			(53,048	)
Loss from discontinued operations			—			—			20			—			—			20
Net (loss) income			(50,553	)		(10,693	)		(32,368	)		2,209			38,337			(53,068	)
Net loss attributable to noncontrolling interest			—			—			—			—			(2,515	)		(2,515	)
Net (loss) income attributable to member of Summit Materials, LLC		$	(50,553	)	$	(10,693	)	$	(32,368	)	$	2,209		$	40,852		$	(50,553	)
Comprehensive (loss) income attributable to member of Summit Materials, LLC		$	(50,553	)	$	(9,875	)	$	(32,368	)	$	2,209		$	40,607		$	(49,980	)
Condensed Consolidating Statements of Cash Flows
For the three months ended March 28, 2015
		Issuers			Wholly-			Non-			Eliminations			Consolidated
					owned			Guarantors
					Guarantors
Net cash (used in) provided by operating activities		$	(37,814	)	$	(26,132	)	$	2,605		$	(167	)	$	(61,508	)
Cash flow from investing activities:
Acquisitions, net of cash acquired			—			—			—			—			—
Purchase of property, plant and equipment			(891	)		(16,453	)		(364	)		—			(17,708	)
Proceeds from the sale of property, plant, and equipment			—			2,703			38			—			2,741
Other			—			(276	)		—			—			(276	)
Net cash used for investing activities			(891	)		(14,026	)		(326	)		—			(15,243	)
Cash flow from financing activities:
Proceeds from investment by member			397,975			—			—			—			397,975
Capital issuance costs			(8,931	)											(8,931	)
Net proceeds from debt issuance			104,000			—			—			—			104,000
Loans received from and payments made on loans from other Summit Companies			(41,265	)		46,345			(3,177	)		(1,903	)		—
Payments on long-term debt			(105,055	)		(2,441	)		—			1,055			(106,441	)
Payments on acquisition-related liabilities			(166	)		(3,866	)		—			—			(4,032	)
Financing costs			(4,055	)		—			—			—			(4,055	)
Net cash provided by (used for) financing activities			342,503			40,038			(3,177	)		(848	)		378,516
Net increase (decrease) in cash			303,798			(120	)		(898	)		(1,015	)		301,765
Cash — Beginning of period			10,837			697			8,793			(7,112	)		13,215
Cash — End of period		$	314,635		$	577		$	7,895		$	(8,127	)	$	314,980
Condensed Consolidating Statements of Cash Flows
For the three months ended March 29, 2014
		Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
					Guarantor			owned			Guarantors
								Guarantors
Net cash used in operating activities		$	(10,964	)	$	(13,844	)	$	(22,564	)	$	(3,183	)	$	180		$	(50,375	)
Cash flow from investing activities:
Acquisitions, net of cash acquired			(182,514	)		—			—			—			—			(182,514	)
Purchase of property, plant and equipment			(1,157	)		(6,448	)		(12,292	)		(44	)		—			(19,941	)
Proceeds from the sale of property, plant, and equipment			—			48			2,083			71			—			2,202
Other			—			—			7			—			—			7
Net cash (used for) provided by investing activities			(183,671	)		(6,400	)		(10,202	)		27			—			(200,246	)
Cash flow from financing activities:
Proceeds from investment by member			24,350						(1,166	)		1,166						24,350
Net proceeds from debt issuance			306,750			—			—			—			—			306,750
Loans received from and payments made on loans from other Summit Companies			(56,210	)		20,240			38,595			(298	)		(2,327	)		—
Payments on long-term debt			(51,057	)		—			(3,257	)		—			—			(54,314	)
Payments on acquisition-related liabilities			—			—			(638	)		—			—			(638	)
Financing costs			(6,309	)		—			—			—			—			(6,309	)
Net cash provided by (used for) financing activities			217,524			20,240			33,534			868			(2,327	)		269,839
Net increase (decrease) in cash			22,889			(4	)		768			(2,288	)		(2,147	)		19,218
Cash — Beginning of period			10,375			9			3,442			3,631			(2,540	)		14,917
Cash — End of period		$	33,264		$	5		$	4,210		$	1,343		$	(4,687	)	$	34,135

Summary_of_Organization_and_Si1

Summary of Organization and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 28, 2015
Initial Public Offering	Initial Public Offering—Summit Inc. commenced operations on March 11, 2015 upon the pricing of the IPO of its Class A common stock. Summit Inc. raised $433.0 million, net of underwriting discounts, through the issuance of 25,555,555 shares of Class A common stock at a public offering price of $18.00 per share. Summit Inc. used the offering proceeds to purchase a number of newly-issued LP Units from Summit Holdings equal to the number of shares of Class A common stock issued to the public. Summit Inc. caused Summit Holdings to use these proceeds (i) to redeem $288.2 million in aggregate principal amount of outstanding 10 1⁄2% Senior Notes due January 31, 2020 (“Senior Notes”) at a redemption price of 100% and an applicable premium thereon; (ii) to purchase 71,428,571 Class B Units of Continental Cement Company, L.L.C. (“Continental Cement”); (iii) to pay a one-time termination fee of $13.8 million primarily to affiliates of the Sponsors in connection with the termination of a transaction and management fee agreement; and (iv) for general corporate purposes. The $288.2 million redemption of Senior Notes was completed in the second quarter of 2015 at a redemption price equal to par plus an applicable premium of $38.2 million plus $5.2 million of accrued and unpaid interest.
Basis of Presentation	Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements of Summit Holdings and the notes thereto as of and for the year ended December 27, 2014 included in Summit Inc.’s prospectus filed with the SEC on March 13, 2015. The Company’s financial position as of December 27, 2014 and the results of operations and cash flows for the three months ended March 28, 2015 have been recast to reflect those of Summit Holdings. The Company continues to follow the accounting policies set forth in those consolidated financial statements. 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 March 28, 2015 and the results of operations and cash flows for the three months ended March 28, 2015 and March 29, 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, 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%.
	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—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. Management adjusts such estimates and assumptions when circumstances dictate. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.
Business and Credit Concentrations	Business and Credit Concentrations—The Company’s operations are conducted primarily across 17 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Kansas, Kentucky, Utah and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that any significant concentrations of credit exist with respect to individual customers or groups of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three months ended March 28, 2015 or March 29, 2014.
Earnings per Share	Earnings per Share—The Company computes basic earnings per share attributable to stockholders by dividing income attributable to Summit Inc. by the weighted-average Class A common shares outstanding. Diluted earnings per share reflects the potential dilution beyond shares for basic earnings per share that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in the Company’s earnings. Since the Class B common shares have no economic value, they are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the Class A common shares are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic or diluted earnings per share.
Fair Value Measurements	Fair Value Measurements—Certain acquisitions made by the Company require the payment of contingent amounts of purchase consideration. These payments are contingent on specified operating results being achieved in periods subsequent to the acquisition and will only be made if earn-out thresholds are achieved. Contingent consideration obligations are measured at fair value each reporting period. Any adjustments to fair value are recognized in earnings in the period identified. Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition-related liabilities:
	Contingent consideration		$	4,187	$	5,379
	The fair value of the contingent consideration obligations approximated their carrying value as of March 28, 2015 and December 27, 2014. The fair values are 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. There were no material valuation adjustments to contingent consideration obligations in the three months ended March 28, 2015 or March 29, 2014.
Financial Instruments	Financial Instruments—The Company’s financial instruments include debt and certain acquisition-related liabilities (deferred consideration and noncompete obligations). The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			21,076		21,076		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			40,058		40,058		37,357		37,357
		-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
		-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 value 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 — On March 17, 2015, upon the consummation of the IPO and the transactions contemplated by a contribution and purchase agreement entered into with the holders of all of the outstanding Class B Units of Continental Cement, Continental Cement became a wholly-owned indirect subsidiary of Summit Holdings. The noncontrolling interests of Continental Cement were acquired for aggregate consideration of $64.1 million, consisting of $35.0 million of cash, 1,029,183 of Class A common shares and $15.0 million aggregate principal amount of non-interest bearing notes payable in six annual installments of $2.5 million, beginning on March 17, 2016.
New Accounting Standards	New Accounting Standards — In April 2015, the FASB issued a new accounting standard to simplify the presentation of debt issuance costs. Accounting Standards Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity will present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. The ASU is effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance will be applied retrospectively to all prior periods (i.e., the balance sheet for each period will be adjusted). Had the Company adopted this guidance as of the current period, both Other Assets (noncurrent) and Long-term Debt as of March 28, 2015 and December 27, 2014, would have decreased by $19.6 million and $17.2 million, respectively.
	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, which gives an employer whose fiscal year-end does not coincide with a calendar month-end (e.g., an entity that has a 52- or 53-week fiscal year) the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month-end that is closest to its fiscal year-end. The ASU is effective for public business entities for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early application is permitted, and the ASU should be applied prospectively. The Company does not expect the adoption of the ASU to have a material effect on its financial position or results of operations.
	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, prescribes a five-step model for revenue recognition that will replace most existing revenue recognition guidance in U.S. GAAP. The ASU will supersede nearly all existing revenue recognition guidance under U.S. GAAP and provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and 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 and will become effective for the Company in the first quarter of 2017. Early adoption is prohibited. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements.
Reclassifications	Reclassifications — Certain amounts in the prior year have been reclassified to conform to the presentation in the consolidated financial statements as of and for the quarter ended March 28, 2015.
Summit Materials, LLC [Member]
Basis of Presentation	Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto as of and for the year ended December 27, 2014 . The Company continues to follow the accounting policies set forth in those consolidated financial statements. 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 March 28, 2015 and the results of operations and cash flows for the three months ended March 28, 2015 and March 29, 2014.
	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 wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. 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 Company, L.L.C. (“Continental Cement”), a 30% redeemable ownership in Continental Cement.
Use of Estimates	Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. Management adjusts such estimates and assumptions when circumstances dictate. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.
Business and Credit Concentrations	Business and Credit Concentrations—The Company’s operations are conducted primarily across 17 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Kansas, Kentucky, Utah and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that any significant concentrations of credit exist with respect to individual customers or groups of customers. No single customer accounted for more than 10% of total revenue in the three months ended March 28, 2015 or March 29, 2014.
Fair Value Measurements	Fair Value Measurements—Certain acquisitions made by the Company require the payment of contingent amounts of purchase consideration. These payments are contingent on specified operating results being achieved in periods subsequent to the acquisition and will only be made if earn-out thresholds are achieved. Contingent consideration obligations are measured at fair value each reporting period. Any adjustments to fair value are recognized in earnings in the period identified. Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition-related liabilities:
	Contingent consideration		$	4,187	$	5,379
	The fair value of the contingent consideration obligations approximated their carrying value as of March 28, 2015 and December 27, 2014. The fair values are 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. There were no material valuation adjustments to contingent consideration obligations in the three months ended March 28, 2015 or March 29, 2014.
Financial Instruments	Financial Instruments—The Company’s financial instruments include debt and certain acquisition-related liabilities (deferred consideration and noncompete obligations). The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			18,576		18,576		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			31,981		31,981		37,357		37,357
		-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
		-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 value 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 — On March 17, 2015, upon the consummation of the IPO and the transactions contemplated by a contribution and purchase agreement entered into with the holders of all of the outstanding Class B Units of Continental Cement, Continental Cement became a wholly-owned indirect subsidiary of Summit LLC. The noncontrolling interests of Continental Cement were acquired for aggregate consideration of $64.1 million, consisting of $35.0 million of cash, 1,029,183 of Class A common shares and $15.0 million aggregate principal amount of non-interest bearing notes payable in six annual installments of $2.5 million, beginning on March 17, 2016. The notes payable is a liability of Summit Holdings and, is therefore excluded from the liabilities of Summit LLC.
New Accounting Standards	New Accounting Standards — In April 2015, the FASB issued a new accounting standard to simplify the presentation of debt issuance costs. Accounting Standards Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity will present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. The ASU is effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance will be applied retrospectively to all prior periods (i.e., the balance sheet for each period will be adjusted). Had the Company adopted this guidance as of the current period, both Other Assets (noncurrent) and Long-term Debt as of March 28, 2015 and December 27, 2014, would have decreased by $19.6 million and $17.2 million, respectively.
	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, which gives an employer whose fiscal year-end does not coincide with a calendar month-end (e.g., an entity that has a 52- or 53-week fiscal year) the ability, as a practical expedient, to measure defined benefit retirement obligations and related plan assets as of the month-end that is closest to its fiscal year-end. The ASU is effective for public business entities for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early application is permitted, and the ASU should be applied prospectively. The Company does not expect the adoption of the ASU to have a material effect on its financial position or results of operations.
	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, prescribes a five-step model for revenue recognition that will replace most existing revenue recognition guidance in U.S. GAAP. The ASU will supersede nearly all existing revenue recognition guidance under U.S. GAAP and provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and 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 and will become effective for the Company in the first quarter of 2017. Early adoption is prohibited. Management is currently assessing the effect that the adoption of this standard will have on the consolidated financial statements.
Reclassifications	Reclassifications — Certain amounts in the prior year have been reclassified to conform to the presentation in the consolidated financial statements as of and for the quarter ended March 28, 2015.

Summary_of_Organization_and_Si2

Summary of Organization and Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 28, 2015
Schedule of Contingent Consideration Obligations Measured at Fair Value	Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition-related liabilities:
	Contingent consideration		$	4,187	$	5,379
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			21,076		21,076		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			40,058		40,058		37,357		37,357
		-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
		-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	Contingent consideration as of March 28, 2015 and December 27, 2014 was:
			March 28,		December 27,
			2015		2014
	Current portion of acquisition-related liabilities:
	Current portion of contingent consideration		$	3,775	$	2,375
	Acquisition- related liabilities:
	Contingent consideration		$	4,187	$	5,379
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of March 28, 2015 and December 27, 2014 was:
			March 28, 2015				December 27, 2014
			Fair Value		Carrying Value		Fair Value		Carrying Value
	Level 2
	Long-term debt(1)			1,105,240		1,062,693		1,101,873		1,064,917
	Level 3
	Current portion of deferred consideration and noncompete obligations(2)			18,576		18,576		16,027		16,027
	Long term portion of deferred consideration and noncompete obligations(3)			31,981		31,981		37,357		37,357
	-1	$5.3 million included in current portion of debt as of March 28, 2015 and December 27, 2014.
	-2	Included in current portion of acquisition-related liabilities on the balance sheet.
	-3	Included in acquisition-related liabilities on the balance sheet.

Accounts_Receivable_Net_Tables

Accounts Receivable, Net (Tables)	3 Months Ended
	Mar. 28, 2015
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,			December 27,
		2015			2014
	Trade accounts receivable	$	100,528		$	131,060
	Retention receivables		10,301			12,053
	Receivables from related parties		928			333
	Accounts receivable		111,757			143,446
	Less: Allowance for doubtful accounts		(1,816	)		(2,144	)
	Accounts receivable, net	$	109,941		$	141,302
Summit Materials, LLC [Member]
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,			December 27,
		2015			2014
	Trade accounts receivable	$	100,528		$	131,060
	Retention receivables		10,301			12,053
	Receivables from related parties		928			333
	Accounts receivable		111,757			143,446
	Less: Allowance for doubtful accounts		(1,816	)		(2,144	)
	Accounts receivable, net	$	109,941		$	141,302

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 28, 2015
Components of Inventories	Inventories consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,		December 27,
		2015		2014
	Aggregate stockpiles	$	90,000	$	88,211
	Finished goods		18,355		8,826
	Work in process		2,065		1,801
	Raw materials		22,887		12,715
	Total	$	133,307	$	111,553
Summit Materials, LLC [Member]
Components of Inventories	Inventories consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,		December 27,
		2015		2014
	Aggregate stockpiles	$	90,000	$	88,211
	Finished goods		18,355		8,826
	Work in process		2,065		1,801
	Raw materials		22,887		12,715
	Total	$	133,307	$	111,553

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 28, 2015
Components of Accrued Expenses	Accrued expenses consisted of the following as of March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Interest		$	15,917	$	32,475
	Payroll and benefits			13,100		20,326
	Capital lease obligations			17,926		17,530
	Insurance			12,469		11,402
	Non-income taxes			5,765		5,520
	Professional fees			3,051		3,299
	Other (1)			13,384		10,944
	Total		$	81,612	$	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 March 28, 2015 and December 27, 2014:
			March 28,		December 27,
			2015		2014
	Interest		$	15,917	$	32,475
	Payroll and benefits			13,100		20,326
	Capital lease obligations			17,926		17,530
	Insurance			12,469		11,402
	Non-income taxes			5,765		5,520
	Professional fees			3,051		3,299
	Other (1)			13,384		10,944
	Total		$	81,612	$	101,496
	-1	Consists primarily of subcontractor and working capital settlement accruals.

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 28, 2015
Schedule of Debt	Debt consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,			December 27,
		2015			2014
	Long-term debt:
	$625.0 million senior notes, including a $25.2 million and $26.5 million net premium at March 28, 2015 and December 27, 2014, respectively		650,225			651,548
	$414.6 million term loan, net of $2.1 million discount at March 28, 2015 and $415.7 million term loan, net of $2.3 million discount at December 27, 2014		412,468			413,369
	Total		1,062,693			1,064,917
	Current portion of long-term debt		5,275			5,275
	Long-term debt	$	1,057,418		$	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 March 28, 2015, are as follows:
	2015 (nine months)	$	4,220
	2016		4,220
	2017		4,220
	2018		3,165
	2019		398,790
	2020		625,000
	Total		1,039,615
	Plus: Original issue net premium		23,078
	Total debt	$	1,062,693
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the three months ended March 28, 2015 and March 29, 2014:
		Deferred financing fees
	Balance — December 27, 2014	$	17,215
	Loan origination fees		4,048
	Amortization		(982	)
	Write off of deferred financing fees		(688	)
	Balance — March 28, 2015	$	19,593
	Balance — December 28, 2013	$	11,485
	Loan origination fees		6,309
	Amortization		(850	)
	Balance — March 29, 2014	$	16,944
Summit Materials, LLC [Member]
Schedule of Debt	Debt consisted of the following as of March 28, 2015 and December 27, 2014:
		March 28,			December 27,
		2015			2014
	Long-term debt:
	$625.0 million senior notes, including a $25.2 million and $26.5 million net premium at March 28, 2015 and December 27, 2014, respectively		650,225			651,548
	$414.6 million term loan, net of $2.1 million discount at March 28, 2015 and
	$415.7 million term loan, net of $2.3 million discount at December 27, 2014		412,468			413,369
	Total		1,062,693			1,064,917
	Current portion of long-term debt		5,275			5,275
	Long-term debt	$	1,057,418		$	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 March 28, 2015, are as follows:
	2015 (nine months)	$	4,220
	2016		4,220
	2017		4,220
	2018		3,165
	2019		398,790
	2020		625,000
	Total		1,039,615
	Plus: Original issue net premium		23,078
	Total debt	$	1,062,693
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the three months ended March 28, 2015 and March 29, 2014:
		Deferred financing fees
	Balance — December 27, 2014	$	17,215
	Loan origination fees		4,048
	Amortization		(982	)
	Write off of deferred financing fees		(688	)
	Balance — March 28, 2015	$	19,593
	Balance — December 28, 2013	$	11,485
	Loan origination fees		6,309
	Amortization		(850	)
	Balance — March 29, 2014	$	16,944

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 28, 2015
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information is as follows:
		Three months ended
		March 28,			March 29,
		2015			2014
	Cash payments:
	Interest	$	39,165		$	19,970
	Income taxes		453			795
	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:
		Three months ended
		March 28,			March 29,
		2015			2014
	Cash payments:
	Interest	$	39,165		$	19,970
	Income taxes		453			795
	Non cash financing activities:
	Purchase of noncontrolling interest in Continental Cement	$	(64,102	)	$	—

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 28, 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
			March 28,			March 29,
			2015			2014
	Revenue:
	West region		$	127,674		$	94,894
	Central region			56,609			47,542
	East region			9,704			8,655
	Total revenue		$	193,987		$	151,091
			Three months ended
			March 28,			March 29,
			2015			2014
	Adjusted EBITDA
	West region		$	11,869		$	1,791
	Central region			710			(423	)
	East region			(7,867	)		(9,338	)
	Corporate and other			(9,687	)		(7,499	)
	Total reportable segments and corporate			(4,975	)		(15,469	)
	Interest expense			24,109			18,819
	Depreciation, depletion, amortization and accretion			26,126			19,356
	Initial public offering costs			28,296			—
	Loss on debt financings			799			—
	Loss from continuing operations before taxes		$	(84,305	)	$	(53,644	)
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash paid for capital expenditures:
	West region		$	5,419		$	4,138
	Central region			8,624			12,401
	East region			2,774			2,245
	Total reportable segments			16,817			18,784
	Corporate and other			891			1,157
	Total capital expenditures		$	17,708		$	19,941
			Three months ended
			March 28,			March 29,
			2015			2014
	Depreciation, depletion, amortization and accretion:
	West region		$	12,088		$	6,747
	Central region			10,072			8,847
	East region			3,477			3,457
	Total reportable segments			25,637			19,051
	Corporate and other			489			305
	Total depreciation, depletion, amortization and accretion		$	26,126		$	19,356
			March 28,			December 27,
			2015			2014
	Total assets:
	West region		$	760,881		$	777,981
	Central region			704,314			704,134
	East region			219,607			221,598
	Total reportable segments			1,684,802			1,703,713
	Corporate and other			333,452			26,064
	Total		$	2,018,254		$	1,729,777
			Three months ended
			March 28,			March 29,
			2015			2014
	Revenue by product:*
	Aggregates		$	52,337		$	31,550
	Cement			11,819			7,707
	Ready-mixed concrete			70,088			42,380
	Asphalt			20,914			24,396
	Paving and related services			43,899			55,857
	Other			(5,070	)		(10,799	)
	Total revenue		$	193,987		$	151,091
		*	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
			March 28,			March 29,
			2015			2014
	Revenue:
	West region		$	127,674		$	94,894
	Central region			56,609			47,542
	East region			9,704			8,655
	Total revenue		$	193,987		$	151,091
			Three months ended
			March 28,			March 29,
			2015			2014
	Adjusted EBITDA
	West region		$	11,869		$	1,791
	Central region			710			(423	)
	East region			(7,867	)		(9,338	)
	Corporate and other			(9,687	)		(7,499	)
	Total reportable segments and corporate			(4,975	)		(15,469	)
	Interest expense			24,109			18,819
	Depreciation, depletion, amortization and accretion			26,126			19,356
	Initial public offering costs			28,296			—
	Loss on debt financings			799			—
	Loss from continuing operations before taxes		$	(84,305	)	$	(53,644	)
			Three months ended
			March 28,			March 29,
			2015			2014
	Cash paid for capital expenditures:
	West region		$	5,419		$	4,138
	Central region			8,624			12,401
	East region			2,774			2,245
	Total reportable segments			16,817			18,784
	Corporate and other			891			1,157
	Total capital expenditures		$	17,708		$	19,941
			Three months ended
			March 28,			March 29,
			2015			2014
	Depreciation, depletion, amortization and accretion:
	West region		$	12,088		$	6,747
	Central region			10,072			8,847
	East region			3,477			3,457
	Total reportable segments			25,637			19,051
	Corporate and other			489			305
	Total depreciation, depletion, amortization and accretion		$	26,126		$	19,356
			March 28,			December 27,
			2015			2014
	Total assets:
	West region		$	760,881		$	777,981
	Central region			704,314			704,134
	East region			219,607			221,598
	Total reportable segments			1,684,802			1,703,713
	Corporate and other			333,452			26,064
	Total		$	2,018,254		$	1,729,777
			Three months ended
			March 28,			March 29,
			2015			2014
	Revenue by product:*
	Aggregates		$	52,337		$	31,550
	Cement			11,819			7,707
	Ready-mixed concrete			70,088			42,380
	Asphalt			20,914			24,396
	Paving and related services			43,899			55,857
	Other			(5,070	)		(10,799	)
	Total revenue		$	193,987		$	151,091
	*	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.

ACCUMULATED_OTHER_COMPREHENSIV1

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables) (Summit Materials, LLC [Member])	3 Months Ended
	Mar. 28, 2015
Summit Materials, LLC [Member]
Accumulated Other Comprehensive Loss	The changes in each component of accumulated other comprehensive loss consisted of the following:
		Pension and			Foreign currency			Accumulated
		Post-			translation			other
		retirement plans			adjustments			comprehensive
								loss
	Balance — December 27, 2014	$	(9,730	)	$	(5,816	)	$	(15,546	)
	Foreign currency translation adjustment		—			(6,299	)		(6,299	)
	Balance — March 28, 2015	$	(9,730	)	$	(12,115	)	$	(21,845	)
	Balance — December 28, 2013	$	(6,045	)	$	—		$	(6,045	)
	Postretirement curtailment adjustment		(942	)		—			(942	)
	Postretirement liability adjustment		1,515			—			1,515
	Balance — March 29, 2014	$	(5,472	)	$	—		$	(5,472	)

SENIOR_NOTES_GUARANTOR_AND_NON1

SENIOR NOTES' GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Tables) (Summit Materials, LLC [Member])	3 Months Ended
	Mar. 28, 2015
Summit Materials, LLC [Member]
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets
	March 28, 2015
		Issuers			Wholly-			Non-			Eliminations			Consolidated
					owned			Guarantors
					Guarantors
	Assets
	Current assets:
	Cash	$	314,635		$	577		$	7,895		$	(8,127	)	$	314,980
	Accounts receivable, net		—			101,089			9,269			(417	)		109,941
	Intercompany receivables		367,129			19,372			5,727			(392,228	)		—
	Cost and estimated earnings in excess of billings		—			11,581			255			—			11,836
	Inventories		—			125,725			7,582			—			133,307
	Other current assets		739			15,485			1,252			—			17,476
	Total current assets		682,503			273,829			31,980			(400,772	)		587,540
	Property, plant and equipment, net		7,436			912,608			28,085			—			948,129
	Goodwill		—			364,309			51,273			—			415,582
	Intangible assets, net		—			14,547			2,344			—			16,891
	Other assets		1,308,994			137,950			1,298			(1,398,130	)		50,112
	Total assets	$	1,998,933		$	1,703,243		$	114,980		$	(1,798,902	)	$	2,018,254
	Liabilities, Redeemable Noncontrolling Interest and Member’s Interest
	Current liabilities:
	Current portion of debt	$	5,275		$	5,266		$	—		$	(5,266	)	$	5,275
	Current portion of acquisition-related liabilities		—			22,351			—			—			22,351
	Accounts payable		5,073			61,530			4,654			(417	)		70,840
	Accrued expenses		25,083			60,750			3,906			(8,127	)		81,612
	Intercompany payables		109,863			278,938			3,427			(392,228	)		—
	Billings in excess of costs and estimated earnings		—			8,309			—			—			8,309
	Total current liabilities		145,294			437,144			11,987			(406,038	)		188,387
	Long-term debt		1,057,418			632,861			—			(632,861	)		1,057,418
	Acquisition-related liabilities		—			36,168			—			—			36,168
	Other noncurrent liabilities		751			94,243			57,546			(55,107	)		97,433
	Total liabilities		1,203,463			1,200,416			69,533			(1,094,006	)		1,379,406
	Total stockholders’ equity/partners’ interest		795,470			502,827			45,447			(704,896	)		638,848
	Total liabilities, redeemable noncontrolling interest and member’s interest	$	1,998,933		$	1,703,243		$	114,980		$	(1,798,902	)	$	2,018,254
	Condensed Consolidating Balance Sheets
	December 27, 2014
		Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
					Guarantor			owned			Guarantors
								Guarantors
	Assets
	Current assets:
	Cash	$	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 March 28, 2015
		Issuers			Wholly-			Non-			Eliminations			Consolidated
					owned			Guarantors
					Guarantors
	Revenue	$	—		$	179,343		$	33,646		$	(19,002	)	$	193,987
	Cost of revenue (excluding items shown separately below)		—			151,226			26,045			(19,002	)		158,269
	General and administrative expenses		37,781			29,151			1,666			—			68,598
	Depreciation, depletion, amortization and accretion		490			24,153			1,483			—			26,126
	Operating (loss) income		(38,271	)		(25,187	)		4,452			—			(59,006	)
	Other (income) expense, net		25,786			739			149			(25,484	)		1,190
	Interest expense		13,798			16,055			881			(6,625	)		24,109
	Income from continuing operations before taxes		(77,855	)		(41,981	)		3,422			32,109			(84,305	)
	Income tax benefit (expense)		—			(4,538	)		70			—			(4,468	)
	Income from continuing operations		(77,855	)		(37,443	)		3,352			32,109			(79,837	)
	Income from discontinued operations		—			—			—			—			—
	Net income		(77,855	)		(37,443	)		3,352			32,109			(79,837	)
	Net income attributable to minority interest		—			—			—			(1,982	)		(1,982	)
	Net income attributable to member of Summit Materials, LLC	$	(77,855	)	$	(37,443	)	$	3,352		$	34,091		$	(77,855	)
	Comprehensive income attributable to member of Summit Materials, LLC	$	(84,154	)	$	(37,443	)	$	(2,947	)	$	40,390		$	(84,154	)
	Condensed Consolidating Statements of Operations
	For the three months ended March 29, 2014
		Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
					Guarantor			owned			Guarantors
								Guarantors
	Revenue	$	—		$	7,707		$	140,410		$	6,332		$	(3,358	)	$	151,091
	Cost of revenue (excluding items shown separately below)		—			10,903			117,624			3,506			(3,358	)		128,675
	General and administrative expenses		7,688			1,674			28,441			276			—			38,079
	Depreciation, depletion, amortization and accretion		304			3,074			15,712			266			—			19,356
	Operating (loss) income		(7,992	)		(7,944	)		(21,367	)		2,284			—			(35,019	)
	Other expense (income), net		36,825			(97	)		(195	)		49			(36,776	)		(194	)
	Interest expense		5,736			2,846			11,772			26			(1,561	)		18,819
	(Loss) income from continuing operations before taxes		(50,553	)		(10,693	)		(32,944	)		2,209			38,337			(53,644	)
	Income tax benefit		—			—			(596	)		—			—			(596	)
	(Loss) income from continuing operations		(50,553	)		(10,693	)		(32,348	)		2,209			38,337			(53,048	)
	Loss from discontinued operations		—			—			20			—			—			20
	Net (loss) income		(50,553	)		(10,693	)		(32,368	)		2,209			38,337			(53,068	)
	Net loss attributable to noncontrolling interest		—			—			—			—			(2,515	)		(2,515	)
	Net (loss) income attributable to member of Summit Materials, LLC	$	(50,553	)	$	(10,693	)	$	(32,368	)	$	2,209		$	40,852		$	(50,553	)
	Comprehensive (loss) income attributable to member of Summit Materials, LLC	$	(50,553	)	$	(9,875	)	$	(32,368	)	$	2,209		$	40,607		$	(49,980	)
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows
	For the three months ended March 28, 2015
		Issuers			Wholly-			Non-			Eliminations			Consolidated
					owned			Guarantors
					Guarantors
	Net cash (used in) provided by operating activities	$	(37,814	)	$	(26,132	)	$	2,605		$	(167	)	$	(61,508	)
	Cash flow from investing activities:
	Acquisitions, net of cash acquired		—			—			—			—			—
	Purchase of property, plant and equipment		(891	)		(16,453	)		(364	)		—			(17,708	)
	Proceeds from the sale of property, plant, and equipment		—			2,703			38			—			2,741
	Other		—			(276	)		—			—			(276	)
	Net cash used for investing activities		(891	)		(14,026	)		(326	)		—			(15,243	)
	Cash flow from financing activities:
	Proceeds from investment by member		397,975			—			—			—			397,975
	Capital issuance costs		(8,931	)											(8,931	)
	Net proceeds from debt issuance		104,000			—			—			—			104,000
	Loans received from and payments made on loans from other Summit Companies		(41,265	)		46,345			(3,177	)		(1,903	)		—
	Payments on long-term debt		(105,055	)		(2,441	)		—			1,055			(106,441	)
	Payments on acquisition-related liabilities		(166	)		(3,866	)		—			—			(4,032	)
	Financing costs		(4,055	)		—			—			—			(4,055	)
	Net cash provided by (used for) financing activities		342,503			40,038			(3,177	)		(848	)		378,516
	Net increase (decrease) in cash		303,798			(120	)		(898	)		(1,015	)		301,765
	Cash — Beginning of period		10,837			697			8,793			(7,112	)		13,215
	Cash — End of period	$	314,635		$	577		$	7,895		$	(8,127	)	$	314,980
	Condensed Consolidating Statements of Cash Flows
	For the three months ended March 29, 2014
		Issuers			Non-Wholly-owned			Wholly-			Non-			Eliminations			Consolidated
					Guarantor			owned			Guarantors
								Guarantors
	Net cash used in operating activities	$	(10,964	)	$	(13,844	)	$	(22,564	)	$	(3,183	)	$	180		$	(50,375	)
	Cash flow from investing activities:
	Acquisitions, net of cash acquired		(182,514	)		—			—			—			—			(182,514	)
	Purchase of property, plant and equipment		(1,157	)		(6,448	)		(12,292	)		(44	)		—			(19,941	)
	Proceeds from the sale of property, plant, and equipment		—			48			2,083			71			—			2,202
	Other		—			—			7			—			—			7
	Net cash (used for) provided by investing activities		(183,671	)		(6,400	)		(10,202	)		27			—			(200,246	)
	Cash flow from financing activities:
	Proceeds from investment by member		24,350						(1,166	)		1,166						24,350
	Net proceeds from debt issuance		306,750			—			—			—			—			306,750
	Loans received from and payments made on loans from other Summit Companies		(56,210	)		20,240			38,595			(298	)		(2,327	)		—
	Payments on long-term debt		(51,057	)		—			(3,257	)		—			—			(54,314	)
	Payments on acquisition-related liabilities		—			—			(638	)		—			—			(638	)
	Financing costs		(6,309	)		—			—			—			—			(6,309	)
	Net cash provided by (used for) financing activities		217,524			20,240			33,534			868			(2,327	)		269,839
	Net increase (decrease) in cash		22,889			(4	)		768			(2,288	)		(2,147	)		19,218
	Cash — Beginning of period		10,375			9			3,442			3,631			(2,540	)		14,917
	Cash — End of period	$	33,264		$	5		$	4,210		$	1,343		$	(4,687	)	$	34,135

Summary_of_Organization_and_Si3

Summary of Organization and Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended	0 Months Ended
	Mar. 28, 2015	Mar. 29, 2014	Dec. 27, 2014	Apr. 30, 2015	Jun. 27, 2015
	Customer	Customer
	State
	Segment
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments	3
Date of incorporation	23-Sep-14
Net proceeds from IPO	$460,000,000
Redeemable noncontrolling interest percentage	40.00%
Number of customers accounted for more than 10% of total revenue	0	0
Number of operating states	17
Reductions recognized in contingent consideration	0	0
Aggregate consideration for acquiring noncontrolling interests	64,100,000
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)	-755,000	-3,202,000
Accounting Standards Update (ASU) 2015-03 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Decrease in other assets (noncurrent)	-19,600,000
Decrease in long-term debt			-17,200,000
Level 3 [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	72.20%
Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Number of operating segments	3
Date of incorporation	23-Sep-14
Redeemable noncontrolling interest percentage	40.00%
Number of customers accounted for more than 10% of total revenue	0	0
Number of operating states	17
Reductions recognized in contingent consideration	0	0
Aggregate consideration for acquiring noncontrolling interests	64,100,000
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)	-755,000	-3,202,000
Summit Materials, LLC [Member] | Accounting Standards Update (ASU) 2015-03 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Decrease in other assets (noncurrent)	-19,600,000
Decrease in long-term debt			-17,200,000
Summit Materials, LLC [Member] | Level 3 [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Discount rate	11.00%
Continental Cement Company, L.L.C. [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage	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%
Ohio Valley Asphalt, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Redeemable noncontrolling interest percentage	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%
Senior Notes [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Debt instrument, face amount	625,000,000		625,000,000
Senior Notes [Member] | Summit Materials, LLC [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Debt instrument, face amount	625,000,000		625,000,000
Senior Notes [Member] | Summit Materials, LLC [Member] | Subsequent Event [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Debt instrument, face amount				288,200,000
Debt Instrument, redemption premium				38,200,000
Accrued and unpaid interest				5,200,000
Sales [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Customer accounted revenue	10.00%	10.00%
Sales [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%
Common Class A [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common 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	1,029,183
Initial Public Offering [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Operations commenced date	11-Mar-15
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] | Class B Units [Member] | Continental Cement Company, L.L.C. [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class B capital units purchased	71,428,571
Initial Public Offering [Member] | Senior Notes [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, interest rate	10.50%
Senior notes, redemption date	31-Jan-20
Senior notes, redemption price percentage	100.00%
Debt instrument, face amount	288,200,000
Debt Instrument, redemption premium	38,200,000
Accrued and unpaid interest	5,200,000
Initial Public Offering [Member] | Senior Notes [Member] | Subsequent Event [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Senior notes, aggregate principal amount redeemed	$288,200,000				$288,200,000
Initial Public Offering [Member] | Common Class A [Member]
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Class A common shares	25,555,555
Class A Common stock offering price per share	$18

Summary_of_Organization_and_Si4

Summary of Organization and Significant Accounting Policies - Schedule of Contingent Consideration Obligations Measured at Fair Value (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Business Acquisition, Contingent Consideration [Line Items]
Current portion of contingent consideration	$3,775	$2,375
Contingent consideration	4,187	5,379
Summit Materials, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Current portion of contingent consideration	3,775	2,375
Contingent consideration	$4,187	$5,379

Summary_of_Organization_and_Si5

Summary of Organization and Significant Accounting Policies - Schedule of Carrying Value and Fair Value of Financial Instruments (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Long-term debt, Carrying Value	$1,062,693	$1,064,917
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, Carrying Value	1,062,693	1,064,917
Level 2 [Member]
Debt Instrument [Line Items]
Long-term debt, Fair Value	1,105,240	1,101,873
Long-term debt, Carrying Value	1,062,693	1,064,917
Level 2 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, Fair Value	1,105,240	1,101,873
Long-term debt, Carrying Value	1,062,693	1,064,917
Level 3 [Member]
Debt Instrument [Line Items]
Current portion of deferred consideration and noncompete obligations, Fair Value	21,076	16,027
Long term portion of deferred consideration and noncompete obligations, Fair Value	40,058	37,357
Current portion of deferred consideration and noncompete obligations, Carrying Value	21,076	16,027
Long term portion of deferred consideration and noncompete obligations, Carrying Value	40,058	37,357
Level 3 [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Current portion of deferred consideration and noncompete obligations, Fair Value	18,576	16,027
Long term portion of deferred consideration and noncompete obligations, Fair Value	31,981	37,357
Current portion of deferred consideration and noncompete obligations, Carrying Value	18,576	16,027
Long term portion of deferred consideration and noncompete obligations, Carrying Value	$31,981	$37,357

Summary_of_Organization_and_Si6

Summary of Organization and Significant Accounting Policies - Schedule of Carrying Value and Fair Value of Financial Instruments (Parenthetical) (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Millions, unless otherwise specified
Debt Instrument [Line Items]
Current portion of debt	$5.30	$5.30
Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Current portion of debt	$5.30	$5.30

Reorganization_Additional_Info

Reorganization - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 28, 2015
Reorganization Items [Line Items]
Number of LP Units outstanding	69,007,297
Vesting period of leverage restoration options	4 years
2015 Omnibus Equity Incentive Plan [Member]
Reorganization Items [Line Items]
Percentage of performance-vesting options	25.00%
General and Administrative Expense Costs [Member]
Reorganization Items [Line Items]
Modification charge recognized in general and administrative costs	14.5
Common Class A [Member]
Reorganization Items [Line Items]
Class A common stock issued at IPO	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	18
Common Class A [Member] | Initial Public Offering [Member]
Reorganization Items [Line Items]
Class A common stock issued at IPO	25,555,555
Class A Common stock offering price per share	18
Class C Units [Member] | Common Class A [Member]
Reorganization Items [Line Items]
Class A common stock issued at IPO	160,333
Class D Units [Member] | Common Class A [Member]
Reorganization Items [Line Items]
Class A common stock issued at IPO	4,358,842

Accounts_Receivable_Net_Summar

Accounts Receivable, Net - Summary of Accounts Receivable, Net (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$100,528	$131,060
Retention receivables	10,301	12,053
Receivables from related parties	928	333
Accounts receivable	111,757	143,446
Less: Allowance for doubtful accounts	-1,816	-2,144
Accounts receivable, net	109,941	141,302
Summit Materials, LLC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	100,528	131,060
Retention receivables	10,301	12,053
Receivables from related parties	928	333
Accounts receivable	111,757	143,446
Less: Allowance for doubtful accounts	-1,816	-2,144
Accounts receivable, net	$109,941	$141,302

Inventories_Components_of_Inve

Inventories - Components of Inventories (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Inventory [Line Items]
Aggregate stockpiles	$90,000	$88,211
Finished goods	18,355	8,826
Work in process	2,065	1,801
Raw materials	22,887	12,715
Total	133,307	111,553
Summit Materials, LLC [Member]
Inventory [Line Items]
Aggregate stockpiles	90,000	88,211
Finished goods	18,355	8,826
Work in process	2,065	1,801
Raw materials	22,887	12,715
Total	$133,307	$111,553

Accrued_Expenses_Components_of

Accrued Expenses - Components of Accrued Expenses (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Schedule Of Accrued Expenses [Line Items]
Interest	$15,917	$32,475
Payroll and benefits	13,100	20,326
Capital lease obligations	17,926	17,530
Insurance	12,469	11,402
Non-income taxes	5,765	5,520
Professional fees	3,051	3,299
Other	13,384	10,944
Total	81,612	101,496
Summit Materials, LLC [Member]
Schedule Of Accrued Expenses [Line Items]
Interest	15,917	32,475
Payroll and benefits	13,100	20,326
Capital lease obligations	17,926	17,530
Insurance	12,469	11,402
Non-income taxes	5,765	5,520
Professional fees	3,051	3,299
Other	13,384	10,944
Total	$81,612	$101,496

Debt_Schedule_of_Debt_Detail

Debt - Schedule of Debt (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Long-term debt:
Long-term debt, total	$1,062,693	$1,064,917
Current portion of long-term debt	5,275	5,275
Long-term debt	1,057,418	1,059,642
Credit Facility [Member]
Long-term debt:
Long-term debt, total	412,468	413,369
Senior Notes [Member]
Long-term debt:
Long-term debt, total	650,225	651,548
Summit Materials, LLC [Member]
Long-term debt:
Long-term debt, total	1,062,693	1,064,917
Current portion of long-term debt	5,275	5,275
Long-term debt	1,057,418	1,059,642
Summit Materials, LLC [Member] | Credit Facility [Member]
Long-term debt:
Long-term debt, total	412,468	413,369
Summit Materials, LLC [Member] | Senior Notes [Member]
Long-term debt:
Long-term debt, total	$650,225	$651,548

Debt_Schedule_of_Debt_Parenthe

Debt - Schedule of Debt (Parenthetical) (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, face value	$625,000,000	$625,000,000
Original issuance discount	25,200,000	26,500,000
Summit Materials, LLC [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, face value	625,000,000	625,000,000
Original issuance discount	25,200,000	26,500,000
Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, face value	414,600,000	415,700,000
Original issuance discount	2,100,000	2,300,000
Credit Facility [Member] | Summit Materials, LLC [Member]
Debt Instrument [Line Items]
Long-term debt, face value	414,600,000	415,700,000
Original issuance discount	$2,100,000	$2,300,000

Debt_Schedule_of_Contractual_P

Debt - Schedule of Contractual Payments of Long-Term Debt (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014
In Thousands, unless otherwise specified
Long Term Debt Maturities Repayments Of Principal [Line Items]
2015 (nine months)	$4,220
2016	4,220
2017	4,220
2018	3,165
2019	398,790
2020	625,000
Total	1,039,615
Plus: Original issue net premium	23,078
Total debt	1,062,693	1,064,917
Summit Materials, LLC [Member]
Long Term Debt Maturities Repayments Of Principal [Line Items]
2015 (nine months)	4,220
2016	4,220
2017	4,220
2018	3,165
2019	398,790
2020	625,000
Total	1,039,615
Plus: Original issue net premium	23,078
Total debt	$1,062,693	$1,064,917

Debt_Additional_Information_De

Debt - Additional Information (Detail)

3 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

Mar. 28, 2015

Mar. 29, 2014

Jan. 15, 2015

Jan. 15, 2015

Mar. 17, 2015

Mar. 28, 2015

Mar. 17, 2015

Mar. 16, 2015

Jan. 15, 2015

Jan. 15, 2015

Jan. 15, 2015

Mar. 28, 2015

Mar. 28, 2015

Dec. 27, 2014

Sep. 08, 2014

Jan. 17, 2014

Jan. 30, 2012

Mar. 28, 2015

Sep. 08, 2014

Jan. 17, 2014

Mar. 28, 2015

Mar. 28, 2015

Mar. 29, 2014

Jan. 15, 2015

Jan. 15, 2015

Jan. 30, 2012

Mar. 17, 2015

Mar. 28, 2015

Mar. 17, 2015

Mar. 11, 2015

Jan. 30, 2012

Jan. 15, 2015

Jan. 15, 2015

Jan. 15, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Dec. 27, 2014

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

Mar. 28, 2015

USD ($)

USD ($)

Prime Rate [Member]

Prime Rate [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Letter of Credit [Member]

Senior Notes [Member]

Senior Notes [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials And Summit Materials Finance Corp [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, LLC [Member]

Summit Materials, INC [Member]

Summit Materials, INC [Member]

Summit Materials, INC [Member]

Summit Materials, INC [Member]

Summit Materials, INC [Member]

COLOMBIA

CANADA

USD ($)

USD ($)

USD ($)

COLOMBIA

CANADA

Mainland [Member]

USD ($)

USD ($)

USD ($)

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes Additional [Member]

Senior Notes Additional [Member]

Senior Notes Additional [Member]

Existing Secured Notes [Member]

USD ($)

USD ($)

Prime Rate [Member]

Prime Rate [Member]

Term Loan Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Senior Secured Credit Facilities [Member]

Senior Secured Credit Facilities [Member]

Letter of Credit [Member]

Senior Notes [Member]

Senior Notes [Member]

Interest Coverage Ratio Fiscal Quarter Started January 1, 2013 Through December 31, 2014 [Member]

Interest Coverage Ratio After December 31, 2014 [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

CAD

CAD

CAD

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

COLOMBIA

CANADA

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

COLOMBIA

CANADA

Mainland [Member]

Federal Funds Effective Rate [Member]

Libor Plus Rate [Member]

Base Rate [Member]

London Interbank Offered Rate (LIBOR) [Member]

USD ($)

Maximum [Member]

USD ($)

USD ($)

USD ($)

Senior Secured Credit Facilities [Member]

Senior Secured Credit Facilities [Member]

Federal Funds Effective Rate [Member]

Libor Plus Rate [Member]

Base Rate [Member]

London Interbank Offered Rate (LIBOR) [Member]

CAD

CAD

CAD

Minimum [Member]

Minimum [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$625,000,000

$625,000,000

$115,000,000

$260,000,000

$250,000,000

$115,000,000

$260,000,000

$250,000,000

$235,000,000

$422,000,000

$625,000,000

$625,000,000

Line of credit facility, maximum borrowing capacity

235,000,000

150,000,000

211,700,000

422,000,000

235,000,000

150,000,000

211,700,000

Proceeds from issuance of debt

104,000,000

306,750,000

409,300,000

104,000,000

306,750,000

Premium of debt instrument

23,078,000

34,300,000

23,078,000

Quarterly principal repayments percentage

0.25%

Frequency of periodic payment

Term debt due on the last business day of each March, June, September and December.

Maturity date

30-Jan-19

Revolving credit facility, maturity date

17-Mar-20

17-Mar-20

Financing fees

-799,000

-799,000

Basis spread on variable rate

0.20%

0.90%

0.20%

0.90%

0.50%

1.00%

2.50%

3.50%

0.50%

1.00%

2.50%

3.50%

Effective interest rate

4.05%

4.05%

Outstanding letters of credit

0

23,300,000

0

23,300,000

First lien leverage ratio

4.51

Interest coverage ratio, maximum

1.7

1.85

Interest expense

22,000,000

17,200,000

22,000,000

17,200,000

Revolving credit commitment

6,000,000

500,000

400,000

6,000,000

500,000

400,000

Debt_Summary_of_Activity_for_D

Debt - Summary of Activity for Deferred Financing Fees (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Deferred Financing Cost [Line Items]
Beginning balance	$17,215	$11,485
Loan origination fees	4,048	6,309
Amortization	-982	-850
Write off of deferred financing fees	-688
Ending balance	19,593	16,944
Summit Materials, LLC [Member]
Deferred Financing Cost [Line Items]
Beginning balance	17,215	11,485
Loan origination fees	4,048	6,309
Amortization	-982	-850
Write off of deferred financing fees	-688
Ending balance	$19,593	$16,944

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 28, 2015	Mar. 29, 2014	Dec. 27, 2014
Income Taxes [Line Items]
Liabilities for uncertain tax positions	$0		$0
Interest and penalties recognized in income tax expense	0	0
Deferred tax assets, net	50,500,000
Valuation allowance	69,000,000
Deferred tax liability, book aggregate reserves	6,900,000
Deferred tax liability, fixed assets	10,900,000
Provision for income taxes	-4,468,000	-596,000
Percentage of benefits to be paid on tax receivable agreement	85.00%
Limited Liability Company [Member]
Income Taxes [Line Items]
Provision for income taxes	0
Summit Materials, LLC [Member]
Income Taxes [Line Items]
Liabilities for uncertain tax positions	0		0
Interest and penalties recognized in income tax expense	0	0
Provision for income taxes	($4,468,000)	($596,000)

Net_Loss_Per_Share_Additional_

Net Loss Per Share - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Mar. 28, 2015	Mar. 28, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Number of antidilutive shares excluded from computation of earnings per share		1,746,210
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Issuance of common stock, Shares	25,555,555	25,555,555
Stock issued in conjunction with the acquisition		1,029,183

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended		0 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2015	Dec. 31, 2012	Dec. 31, 2011	Apr. 02, 2015	Dec. 27, 2014
Loss Contingencies [Line Items]
Amount funded for loss incurred by joint venture	$8.80	$4	$4.80
Accrual recorded in other noncurrent liabilities	4.3				4.3
Percentage of ownership interest in joint venture	40.00%
Unapproved change orders and claims	3.9				3.9
Unapproved change orders within accounts receivable	1.2				1.2
Unapproved change orders within costs in excess of billings	0.5				0.5
Unapproved change orders within other current assets	2.2				2.2
Summit Materials, LLC [Member]
Loss Contingencies [Line Items]
Amount funded for loss incurred by joint venture	8.8	4	4.8
Accrual recorded in other noncurrent liabilities	4.3				4.3
Percentage of ownership interest in joint venture	40.00%
Unapproved change orders and claims	3.9				3.9
Unapproved change orders within accounts receivable	1.2				1.2
Unapproved change orders within costs in excess of billings	0.5				0.5
Unapproved change orders within other current assets	2.2				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
Subsequent Event [Member]
Loss Contingencies [Line Items]
Value of damages sought				29.4
Subsequent Event [Member] | Summit Materials, LLC [Member]
Loss Contingencies [Line Items]
Value of damages sought				$29.40

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Cash payments:
Interest	$39,165	$19,970
Income taxes	453	795
Non cash financing activities:
Purchase of noncontrolling interest in Continental Cement	-29,102
Summit Materials, LLC [Member]
Cash payments:
Interest	39,165	19,970
Income taxes	453	795
Non cash financing activities:
Purchase of noncontrolling interest in Continental Cement	($64,102)

Segment_Information_Additional

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 28, 2015
	Segment
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_of

Segment Information - Summary of Financial Data for Company's Reportable Business Segments (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014	Dec. 27, 2014
Segment Reporting Information [Line Items]
Total revenue	$193,987	$151,091
Total capital expenditures	17,708	19,941
Income (loss) from continuing operations before taxes	-84,305	-53,644
Interest expense	24,109	18,819
Depreciation, depletion, amortization and accretion	26,126	19,356
Total assets	2,018,254		1,729,777
Loss on debt financings	799
Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	193,987	151,091
Total capital expenditures	17,708	19,941
Income (loss) from continuing operations before taxes	-84,305	-53,644
Interest expense	24,109	18,819
Depreciation, depletion, amortization and accretion	26,126	19,356
Total assets	2,018,254		1,729,777
Loss on debt financings	799
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	16,817	18,784
Depreciation, depletion, amortization and accretion	25,637	19,051
Total assets	1,684,802		1,703,713
Operating Segments [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	16,817	18,784
Depreciation, depletion, amortization and accretion	25,637	19,051
Total assets	1,684,802		1,703,713
Operating Segments [Member] | Aggregates [Member]
Segment Reporting Information [Line Items]
Total revenue	52,337	31,550
Operating Segments [Member] | Aggregates [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	52,337	31,550
Operating Segments [Member] | Cement [Member]
Segment Reporting Information [Line Items]
Total revenue	11,819	7,707
Operating Segments [Member] | Cement [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	11,819	7,707
Operating Segments [Member] | Ready Mixed Concrete [Member]
Segment Reporting Information [Line Items]
Total revenue	70,088	42,380
Operating Segments [Member] | Ready Mixed Concrete [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	70,088	42,380
Operating Segments [Member] | Asphalt [Member]
Segment Reporting Information [Line Items]
Total revenue	20,914	24,396
Operating Segments [Member] | Asphalt [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	20,914	24,396
Operating Segments [Member] | Paving And Related Services [Member]
Segment Reporting Information [Line Items]
Total revenue	43,899	55,857
Operating Segments [Member] | Paving And Related Services [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	43,899	55,857
Operating Segments [Member] | West Region [Member]
Segment Reporting Information [Line Items]
Total revenue	127,674	94,894
Total capital expenditures	5,419	4,138
Income (loss) from continuing operations before taxes	11,869	1,791
Depreciation, depletion, amortization and accretion	12,088	6,747
Total assets	760,881		777,981
Operating Segments [Member] | West Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	127,674	94,894
Total capital expenditures	5,419	4,138
Income (loss) from continuing operations before taxes	11,869	1,791
Depreciation, depletion, amortization and accretion	12,088	6,747
Total assets	760,881		777,981
Operating Segments [Member] | Central Region [Member]
Segment Reporting Information [Line Items]
Total revenue	56,609	47,542
Total capital expenditures	8,624	12,401
Income (loss) from continuing operations before taxes	710	-423
Depreciation, depletion, amortization and accretion	10,072	8,847
Total assets	704,314		704,134
Operating Segments [Member] | Central Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	56,609	47,542
Total capital expenditures	8,624	12,401
Income (loss) from continuing operations before taxes	710	-423
Depreciation, depletion, amortization and accretion	10,072	8,847
Total assets	704,314		704,134
Operating Segments [Member] | East Region [Member]
Segment Reporting Information [Line Items]
Total revenue	9,704	8,655
Total capital expenditures	2,774	2,245
Income (loss) from continuing operations before taxes	-7,867	-9,338
Depreciation, depletion, amortization and accretion	3,477	3,457
Total assets	219,607		221,598
Operating Segments [Member] | East Region [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	9,704	8,655
Total capital expenditures	2,774	2,245
Income (loss) from continuing operations before taxes	-7,867	-9,338
Depreciation, depletion, amortization and accretion	3,477	3,457
Total assets	219,607		221,598
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	891	1,157
Income (loss) from continuing operations before taxes	-9,687	-7,499
Depreciation, depletion, amortization and accretion	489	305
Total assets	333,452		26,064
Corporate and Other [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	891	1,157
Income (loss) from continuing operations before taxes	-9,687	-7,499
Depreciation, depletion, amortization and accretion	489	305
Total assets	333,452		26,064
Operating Segment and Corporate and Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before taxes	-4,975	-15,469
Operating Segment and Corporate and Other [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before taxes	-4,975	-15,469
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Interest expense	24,109	18,819
Depreciation, depletion, amortization and accretion	26,126	19,356
Initial public offering costs	28,296
Loss on debt financings	799
Segment Reconciling Items [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Interest expense	24,109	18,819
Depreciation, depletion, amortization and accretion	26,126	19,356
Initial public offering costs	28,296
Loss on debt financings	799
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue	-5,070	-10,799
Intersegment Eliminations [Member] | Summit Materials, LLC [Member]
Segment Reporting Information [Line Items]
Total revenue	($5,070)	($10,799)

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended
	Sep. 30, 2014	Jan. 31, 2014	Mar. 28, 2015	Mar. 29, 2014	Mar. 11, 2015	Dec. 27, 2014
Related Party Transaction [Line Items]
Transaction fees paid			$1,700,000	$1,700,000
Related party transactions	5,750,000	13,000,000
Assets sold to related party				2,300,000
Summit Materials, LLC [Member]
Related Party Transaction [Line Items]
Management fee agreement termination date			17-Mar-15
Management fee paid as of termination			13,800,000
Transaction fees paid				1,700,000
Related party transactions	5,750,000	13,000,000
Assets sold to related party				2,300,000
Blackstone Management Partners L.L.C. [Member]
Related Party Transaction [Line Items]
Consideration of Consolidated profit			$300,000 or 2.0% which ever is higher
Payment for services			300,000
Management fees incurred			1,000,000	900,000
Management fee agreement termination date			17-Mar-15
Management fee paid as of termination			13,800,000
Percentage transaction fee on value of entity acquired			1.00%
Consideration paid / received on assets acquired / disposed			1.00%
Blackstone Management Partners L.L.C. [Member] | Summit Materials, LLC [Member]
Related Party Transaction [Line Items]
Consideration of Consolidated profit			$300,000 or 2.0% which ever is higher
Payment for services			300,000
Management fees incurred			1,000,000	900,000
Management fee paid as of termination			13,400,000
Percentage transaction fee on value of entity acquired			1.00%
Consideration paid / received on assets acquired / disposed			1.00%
Blackstone And Affiliates [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
Continental Cement Company, L.L.C. [Member]
Related Party Transaction [Line Items]
Sales to related parties				1,700,000	1,400,000
Accounts receivables due from related parties						200,000
Non controlling interest owned				$700,000

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	0 Months Ended
	Apr. 30, 2015	Apr. 16, 2015	Mar. 28, 2015	Dec. 27, 2014
Senior Notes [Member]
Subsequent Event [Line Items]
Debt instrument, face amount			$625,000,000	$625,000,000
Senior Notes [Member] | Summit Materials, LLC [Member]
Subsequent Event [Line Items]
Debt instrument, face amount			625,000,000	625,000,000
Subsequent Event [Member] | Senior Notes [Member] | Summit Materials, LLC [Member]
Subsequent Event [Line Items]
Debt instrument, face amount	288,200,000
Debt Instrument, redemption premium	38,200,000
Accrued and unpaid interest	5,200,000
Davenport Acquisition [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Aggregate cash consideration to be paid		450,000,000
Davenport Acquisition [Member] | Subsequent Event [Member] | Summit Materials, LLC [Member]
Subsequent Event [Line Items]
Aggregate cash consideration to be paid		$450,000,000

Recovered_Sheet1

Accumulated Other Comprehensive Loss - Summary of Changes in Each Component of Accumulated Comprehensive Income Loss (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014	Dec. 27, 2014	Dec. 28, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment	($6,299)
Postretirement adjustment		2,164
Summit Materials, LLC [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment	-6,299
Postretirement adjustment		2,164
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	-6,045
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] | Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-5,816
Foreign currency translation adjustment	-6,299
Ending balance	-12,115
Summit Materials, LLC [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-15,546			-6,045
Foreign currency translation adjustment	-6,299
Ending balance	-21,845	-5,472		-6,045
Summit Materials, LLC [Member] | AOCI Attributable to Parent [Member] | Postretirement Curtailment Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment		-942
Summit Materials, LLC [Member] | AOCI Attributable to Parent [Member] | Postretirement Liability Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Postretirement adjustment		$1,515

Recovered_Sheet2

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Balance Sheets (Detail) (USD $)	Mar. 28, 2015	Dec. 27, 2014	Mar. 29, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified
Current assets:
Cash	$314,980	$13,215	$37,402	$18,184
Accounts receivable, net	109,941	141,302
Cost and estimated earnings in excess of billings	11,836	10,174
Inventories	133,307	111,553
Other current assets	17,476	17,172
Total current assets	587,540	293,416
Property, plant and equipment, net	948,129	950,601
Goodwill	415,582	419,270
Intangible assets, net	16,891	17,647
Other assets	50,112	48,843
Total assets	2,018,254	1,729,777
Current liabilities:
Current portion of debt	5,275	5,275
Current portion of acquisition-related liabilities	24,851	18,402
Accounts payable	70,840	78,854
Accrued expenses	81,612	101,496
Billings in excess of costs and estimated earnings	8,309	8,958
Total current liabilities	190,887	212,985
Long-term debt	1,057,418	1,059,642
Acquisition-related liabilities	44,245	42,736
Other noncurrent liabilities	97,433	93,691
Total liabilities	1,389,983	1,409,054
Redeemable noncontrolling interest		33,740		286,817
Total liabilities, redeemable noncontrolling interest and member's interest	2,018,254	1,729,777
Summit Materials, LLC [Member]
Current assets:
Cash	314,980	13,215	34,135	14,917
Accounts receivable, net	109,941	141,302
Cost and estimated earnings in excess of billings	11,836	10,174
Inventories	133,307	111,553
Other current assets	17,476	17,172
Total current assets	587,540	293,416
Property, plant and equipment, net	948,129	950,601
Goodwill	415,582	419,270
Intangible assets, net	16,891	17,647
Other assets	50,112	48,843
Total assets	2,018,254	1,729,777
Current liabilities:
Current portion of debt	5,275	5,275
Current portion of acquisition-related liabilities	22,351	18,402
Accounts payable	70,840	78,854
Accrued expenses	81,612	101,496
Billings in excess of costs and estimated earnings	8,309	8,958
Total current liabilities	188,387	212,985
Long-term debt	1,057,418	1,059,642
Acquisition-related liabilities	36,168	42,736
Other noncurrent liabilities	97,433	93,691
Total liabilities	1,379,406	1,409,054
Redeemable noncontrolling interest		33,740
Total stockholders' equity/partners' interest	638,848	286,983
Total liabilities, redeemable noncontrolling interest and member's interest	2,018,254	1,729,777
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Current assets:
Cash	-8,127	-7,112	-4,687	-2,540
Accounts receivable, net	-417	-1,233
Intercompany receivables	-392,228	-415,030
Other current assets		-1,853
Total current assets	-400,772	-425,228
Other assets	-1,398,130	-1,256,418
Total assets	-1,798,902	-1,681,646
Current liabilities:
Current portion of debt	-5,266	-5,263
Accounts payable	-417	-1,233
Accrued expenses	-8,127	-8,965
Intercompany payables	-392,228	-415,030
Total current liabilities	-406,038	-430,491
Long-term debt	-632,861	-633,917
Other noncurrent liabilities	-55,107	-55,107
Total liabilities	-1,094,006	-1,119,515
Redeemable noncontrolling interest		33,740
Redeemable members' interest		-34,543
Total stockholders' equity/partners' interest	-704,896	-561,328
Total liabilities, redeemable noncontrolling interest and member's interest	-1,798,902	-1,681,646
Summit Materials, LLC [Member] | Issuers [Member]
Current assets:
Cash	314,635	10,837	33,264	10,375
Accounts receivable, net		1
Intercompany receivables	367,129	376,344
Other current assets	739	7,148
Total current assets	682,503	394,330
Property, plant and equipment, net	7,436	7,035
Other assets	1,308,994	1,153,204
Total assets	1,998,933	1,554,569
Current liabilities:
Current portion of debt	5,275	5,275
Current portion of acquisition-related liabilities		166
Accounts payable	5,073	3,655
Accrued expenses	25,083	37,101
Intercompany payables	109,863	162,728
Total current liabilities	145,294	208,925
Long-term debt	1,057,418	1,059,642
Other noncurrent liabilities	751	796
Total liabilities	1,203,463	1,269,363
Total stockholders' equity/partners' interest	795,470	285,206
Total liabilities, redeemable noncontrolling interest and member's interest	1,998,933	1,554,569
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Current assets:
Cash	577	695	4,210	3,442
Accounts receivable, net	101,089	124,380
Intercompany receivables	19,372	30,539
Cost and estimated earnings in excess of billings	11,581	9,819
Inventories	125,725	98,188
Other current assets	15,485	9,638
Total current assets	273,829	273,259
Property, plant and equipment, net	912,608	610,717
Goodwill	364,309	340,969
Intangible assets, net	14,547	14,245
Other assets	137,950	125,462
Total assets	1,703,243	1,364,652
Current liabilities:
Current portion of debt	5,266	3,990
Current portion of acquisition-related liabilities	22,351	18,236
Accounts payable	61,530	65,018
Accrued expenses	60,750	59,477
Intercompany payables	278,938	245,416
Billings in excess of costs and estimated earnings	8,309	8,931
Total current liabilities	437,144	401,068
Long-term debt	632,861	480,599
Acquisition-related liabilities	36,168	42,736
Other noncurrent liabilities	94,243	65,479
Total liabilities	1,200,416	989,882
Total stockholders' equity/partners' interest	502,827	374,770
Total liabilities, redeemable noncontrolling interest and member's interest	1,703,243	1,364,652
Summit Materials, LLC [Member] | Non-Guarantor Subsidiaries [Member]
Current assets:
Cash	7,895	8,793	1,343	3,631
Accounts receivable, net	9,269	11,525
Intercompany receivables	5,727	4,052
Cost and estimated earnings in excess of billings	255	355
Inventories	7,582	4,669
Other current assets	1,252	1,775
Total current assets	31,980	31,169
Property, plant and equipment, net	28,085	30,325
Goodwill	51,273	55,177
Intangible assets, net	2,344	2,860
Other assets	1,298	1,362
Total assets	114,980	120,893
Current liabilities:
Accounts payable	4,654	4,569
Accrued expenses	3,906	3,705
Intercompany payables	3,427	2,834
Billings in excess of costs and estimated earnings		27
Total current liabilities	11,987	11,135
Other noncurrent liabilities	57,546	57,736
Total liabilities	69,533	68,871
Total stockholders' equity/partners' interest	45,447	52,022
Total liabilities, redeemable noncontrolling interest and member's interest	114,980	120,893
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Current assets:
Cash		2	5	9
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

Recovered_Sheet3

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Operations (Detail) (USD $)	1 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 11, 2015	Mar. 28, 2015	Mar. 29, 2014
Condensed Financial Statements, Captions [Line Items]
Revenue			$193,987	$151,091
Cost of revenue (excluding items shown separately below)			158,269	128,675
Depreciation, depletion, amortization and accretion			26,126	19,356
Operating (loss) income			-59,006	-35,019
Interest expense			24,109	18,819
(Loss) income from continuing operations before taxes			-84,305	-53,644
Income tax benefit			-4,468	-596
(Loss) income from continuing operations			-79,837	-53,048
Income from discontinued operations				20
Net (loss) income	-79,837	-41,415	-79,837	-53,068
Net (loss) income attributable to member of Summit Materials, LLC			-10,151
Comprehensive (loss) income attributable to member of Summit Materials, LLC			-11,201
Summit Materials, LLC [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue			193,987	151,091
Cost of revenue (excluding items shown separately below)			158,269	128,675
General and administrative expenses			68,598	38,079
Depreciation, depletion, amortization and accretion			26,126	19,356
Operating (loss) income			-59,006	-35,019
Other (income) expense, net			1,190	-194
Interest expense			24,109	18,819
(Loss) income from continuing operations before taxes			-84,305	-53,644
Income tax benefit			-4,468	-596
(Loss) income from continuing operations			-79,837	-53,048
Income from discontinued operations				20
Net (loss) income			-79,837	-53,068
Net income attributable to minority interest			-1,982	-2,515
Net (loss) income attributable to member of Summit Materials, LLC			67,704	50,553
Comprehensive (loss) income attributable to member of Summit Materials, LLC			-84,154	-49,980
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue			-19,002	-3,358
Cost of revenue (excluding items shown separately below)			-19,002	-3,358
Other (income) expense, net			-25,484	-36,776
Interest expense			-6,625	-1,561
(Loss) income from continuing operations before taxes			32,109	38,337
(Loss) income from continuing operations			32,109	38,337
Net (loss) income			32,109	38,337
Net income attributable to minority interest			-1,982	-2,515
Net (loss) income attributable to member of Summit Materials, LLC			34,091	40,852
Comprehensive (loss) income attributable to member of Summit Materials, LLC			40,390	40,607
Summit Materials, LLC [Member] | Issuers [Member]
Condensed Financial Statements, Captions [Line Items]
General and administrative expenses			37,781	7,688
Depreciation, depletion, amortization and accretion			490	304
Operating (loss) income			-38,271	-7,992
Other (income) expense, net			25,786	36,825
Interest expense			13,798	5,736
(Loss) income from continuing operations before taxes			-77,855	-50,553
(Loss) income from continuing operations			-77,855	-50,553
Net (loss) income			-77,855	-50,553
Net (loss) income attributable to member of Summit Materials, LLC			-77,855	-50,553
Comprehensive (loss) income attributable to member of Summit Materials, LLC			-84,154	-50,553
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue			179,343	140,410
Cost of revenue (excluding items shown separately below)			151,226	117,624
General and administrative expenses			29,151	28,441
Depreciation, depletion, amortization and accretion			24,153	15,712
Operating (loss) income			-25,187	-21,367
Other (income) expense, net			739	-195
Interest expense			16,055	11,772
(Loss) income from continuing operations before taxes			-41,981	-32,944
Income tax benefit			-4,538	-596
(Loss) income from continuing operations			-37,443	-32,348
Income from discontinued operations				20
Net (loss) income			-37,443	-32,368
Net (loss) income attributable to member of Summit Materials, LLC			-37,443	-32,368
Comprehensive (loss) income attributable to member of Summit Materials, LLC			-37,443	-32,368
Summit Materials, LLC [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue			33,646	6,332
Cost of revenue (excluding items shown separately below)			26,045	3,506
General and administrative expenses			1,666	276
Depreciation, depletion, amortization and accretion			1,483	266
Operating (loss) income			4,452	2,284
Other (income) expense, net			149	49
Interest expense			881	26
(Loss) income from continuing operations before taxes			3,422	2,209
Income tax benefit			70
(Loss) income from continuing operations			3,352	2,209
Net (loss) income			3,352	2,209
Net (loss) income attributable to member of Summit Materials, LLC			3,352	2,209
Comprehensive (loss) income attributable to member of Summit Materials, LLC			-2,947	2,209
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue				7,707
Cost of revenue (excluding items shown separately below)				10,903
General and administrative expenses				1,674
Depreciation, depletion, amortization and accretion				3,074
Operating (loss) income				-7,944
Other (income) expense, net				-97
Interest expense				2,846
(Loss) income from continuing operations before taxes				-10,693
(Loss) income from continuing operations				-10,693
Net (loss) income				-10,693
Net (loss) income attributable to member of Summit Materials, LLC				-10,693
Comprehensive (loss) income attributable to member of Summit Materials, LLC				($9,875)

Senior_Notes_Guarantor_and_Non2

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Cash Flows (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2015	Mar. 29, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	($61,508)	($50,375)
Cash flow from investing activities:
Acquisitions, net of cash acquired		-182,514
Purchase of property, plant and equipment	-17,708	-19,941
Proceeds from the sale of property, plant, and equipment	2,741	2,202
Other	-276	7
Net cash (used for) provided by investing activities	-15,243	-200,246
Cash flow from financing activities:
Capital issuance costs	-35,956
Net proceeds from debt issuance	104,000	306,750
Payments on acquisition-related liabilities	-4,032	-638
Net cash provided by (used for) financing activities	378,516	269,839
Net increase (decrease) in cash	301,765	19,218
Cash - Beginning of period	13,215	18,184
Cash - end of period	314,980	37,402
Summit Materials, LLC [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	-61,508	-50,375
Cash flow from investing activities:
Acquisitions, net of cash acquired		-182,514
Purchase of property, plant and equipment	-17,708	-19,941
Proceeds from the sale of property, plant, and equipment	2,741	2,202
Other	-276	7
Net cash (used for) provided by investing activities	-15,243	-200,246
Cash flow from financing activities:
Proceeds from investment by member	397,975	24,350
Capital issuance costs	-8,931
Net proceeds from debt issuance	104,000	306,750
Payments on long-term debt	-106,441	-54,314
Payments on acquisition-related liabilities	-4,032	-638
Financing costs	-4,055	-6,309
Net cash provided by (used for) financing activities	378,516	269,839
Net increase (decrease) in cash	301,765	19,218
Cash - Beginning of period	13,215	14,917
Cash - end of period	314,980	34,135
Summit Materials, LLC [Member] | Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	-167	180
Cash flow from financing activities:
Loans received from and payments made on loans from other Summit Companies	-1,903	-2,327
Payments on long-term debt	1,055
Net cash provided by (used for) financing activities	-848	-2,327
Net increase (decrease) in cash	-1,015	-2,147
Cash - Beginning of period	-7,112	-2,540
Cash - end of period	-8,127	-4,687
Summit Materials, LLC [Member] | Issuers [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	-37,814	-10,964
Cash flow from investing activities:
Acquisitions, net of cash acquired		-182,514
Purchase of property, plant and equipment	-891	-1,157
Net cash (used for) provided by investing activities	-891	-183,671
Cash flow from financing activities:
Proceeds from investment by member	397,975	24,350
Capital issuance costs	-8,931
Net proceeds from debt issuance	104,000	306,750
Loans received from and payments made on loans from other Summit Companies	-41,265	-56,210
Payments on long-term debt	-105,055	-51,057
Payments on acquisition-related liabilities	-166
Financing costs	-4,055	-6,309
Net cash provided by (used for) financing activities	342,503	217,524
Net increase (decrease) in cash	303,798	22,889
Cash - Beginning of period	10,837	10,375
Cash - end of period	314,635	33,264
Summit Materials, LLC [Member] | Wholly Owned Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	-26,132	-22,564
Cash flow from investing activities:
Purchase of property, plant and equipment	-16,453	-12,292
Proceeds from the sale of property, plant, and equipment	2,703	2,083
Other	-276	7
Net cash (used for) provided by investing activities	-14,026	-10,202
Cash flow from financing activities:
Proceeds from investment by member		-1,166
Loans received from and payments made on loans from other Summit Companies	46,345	38,595
Payments on long-term debt	-2,441	-3,257
Payments on acquisition-related liabilities	-3,866	-638
Net cash provided by (used for) financing activities	40,038	33,534
Net increase (decrease) in cash	-120	768
Cash - Beginning of period	695	3,442
Cash - end of period	577	4,210
Summit Materials, LLC [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	2,605	-3,183
Cash flow from investing activities:
Purchase of property, plant and equipment	-364	-44
Proceeds from the sale of property, plant, and equipment	38	71
Net cash (used for) provided by investing activities	-326	27
Cash flow from financing activities:
Proceeds from investment by member		1,166
Loans received from and payments made on loans from other Summit Companies	-3,177	-298
Net cash provided by (used for) financing activities	-3,177	868
Net increase (decrease) in cash	-898	-2,288
Cash - Beginning of period	8,793	3,631
Cash - end of period	7,895	1,343
Summit Materials, LLC [Member] | Non Wholly Owned Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities		-13,844
Cash flow from investing activities:
Purchase of property, plant and equipment		-6,448
Proceeds from the sale of property, plant, and equipment		48
Net cash (used for) provided by investing activities		-6,400
Cash flow from financing activities:
Loans received from and payments made on loans from other Summit Companies		20,240
Net cash provided by (used for) financing activities		20,240
Net increase (decrease) in cash		-4
Cash - Beginning of period		9
Cash - end of period		$5