Summit Materials (SUM) 10-K/A 20 Feb 19 2018 FY Annual report (amended) Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 29, 2018	Jan. 30, 2019	Jun. 30, 2018	Jul. 01, 2017
Document Information [Line Items]
Entity Registrant Name	Summit Materials, Inc.
Entity Central Index Key	1,621,563
Document Type	10-K/A
Document Period End Date	Dec. 29, 2018
Amendment Flag	true
Amendment Description	Summit Materials, Inc. (the “Company) files this Amendment No. 1 (“Amendment No. 1”) to its Annual Report on Form 10-K for the year ended December 29, 2018 filed with the Securities and Exchange Commission (“SEC”) on February 6, 2019 (the “Original 10-K”) at the request of KPMG LLP to provide an amended report of its independent registered public accounting firm (the “KPMG report”) that includes a statement inadvertently omitted from the previously filed version that confirms that the Company’s independent registered accounting firm did not audit the internal controls over financial reporting for the consolidated financial statements of Summit Materials, LLC whose consolidated financial statements were filed as Exhibit 99.1 to the Company’s Original 10-K. The KPMG report, as replaced in Amendment No. 1, does not modify KPMG LLP's unqualified opinion on the Summit Materials, LLC consolidated financial statements included in the Original 10-K.                   As required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), currently-dated certifications from the Company’s Chief Executive Officer and Chief Financial Officer have been included as exhibits to this Amendment No. 1. Furthermore, pursuant to Rule 12b-15 promulgated under the Exchange Act, the Company has repeated the entire text of Item 8 and Item 15 of the Original 10-K in this Amendment No. 1, however, there have been no changes to the text of such items other than to replace the KPMG report as described above and to file an updated consent of KPMG LLP as Exhibit 23.1.                   Amendment No. 1 speaks as of the date of the Original 10-K, does not reflect events that may have occurred after the date of the Original 10-K and does not modify or update in any way the disclosures made in the Original 10-K, except as described above. Accordingly, Amendment No. 1 should be read in conjunction with the Original 10-K and with the Company’s other filings with the SEC subsequent to the filing of the Original 10-K, including any amendments thereto.
Current Fiscal Year End Date	--12-29
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float				$ 3,100,000,000
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		111,671,837
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		99
Summit Materials, LLC
Document Information [Line Items]
Entity Registrant Name	Summit Materials, LLC
Entity Central Index Key	1,571,371
Document Type	10-K/A
Document Period End Date	Dec. 29, 2018
Amendment Flag	true
Amendment Description	Summit Materials, Inc. (the “Company) files this Amendment No. 1 (“Amendment No. 1”) to its Annual Report on Form 10-K for the year ended December 29, 2018 filed with the Securities and Exchange Commission (“SEC”) on February 6, 2019 (the “Original 10-K”) at the request of KPMG LLP to provide an amended report of its independent registered public accounting firm (the “KPMG report”) that includes a statement inadvertently omitted from the previously filed version that confirms that the Company’s independent registered accounting firm did not audit the internal controls over financial reporting for the consolidated financial statements of Summit Materials, LLC whose consolidated financial statements were filed as Exhibit 99.1 to the Company’s Original 10-K. The KPMG report, as replaced in Amendment No. 1, does not modify KPMG LLP's unqualified opinion on the Summit Materials, LLC consolidated financial statements included in the Original 10-K.                   As required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), currently-dated certifications from the Company’s Chief Executive Officer and Chief Financial Officer have been included as exhibits to this Amendment No. 1. Furthermore, pursuant to Rule 12b-15 promulgated under the Exchange Act, the Company has repeated the entire text of Item 8 and Item 15 of the Original 10-K in this Amendment No. 1, however, there have been no changes to the text of such items other than to replace the KPMG report as described above and to file an updated consent of KPMG LLP as Exhibit 23.1.                   Amendment No. 1 speaks as of the date of the Original 10-K, does not reflect events that may have occurred after the date of the Original 10-K and does not modify or update in any way the disclosures made in the Original 10-K, except as described above. Accordingly, Amendment No. 1 should be read in conjunction with the Original 10-K and with the Company’s other filings with the SEC subsequent to the filing of the Original 10-K, including any amendments thereto.
Current Fiscal Year End Date	--12-29
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Current assets:
Cash and cash equivalents	$ 128,508	$ 383,556
Accounts receivable, net	214,518	198,330
Costs and estimated earnings in excess of billings	18,602	9,512
Inventories	213,851	184,439
Other current assets	16,061	7,764
Total current assets	591,540	783,601
Property, plant and equipment	1,780,132	1,615,424
Goodwill	1,192,028	1,036,320
Intangible assets	18,460	16,833
Deferred tax assets	225,397	284,092
Other assets	50,084	51,063
Total assets	3,857,641	3,787,333
Current liabilities:
Current portion of debt	6,354	4,765
Current portion of acquisition-related liabilities	34,270	14,087
Accounts payable	107,702	98,744
Accrued expenses	100,491	116,629
Billings in excess of costs and estimated earnings	11,840	15,750
Total current liabilities	260,657	249,975
Long-term debt	1,807,502	1,810,833
Acquisition-related liabilities	49,468	58,135
Tax receivable agreement liability	309,674	331,340
Other noncurrent liabilities	88,195	65,329
Total liabilities	2,515,496	2,515,612
Commitments and contingencies (see note 16)
Stockholders' equity / Member's interest
Additional paid-in capital	1,194,204	1,154,220
Accumulated earnings (deficit)	129,739	95,833
Accumulated other comprehensive income	2,681	7,386
Stockholders’ equity	1,327,741	1,258,543
Noncontrolling interest in Summit Holdings	14,404	13,178
Total stockholders’ equity	1,342,145	1,271,721
Total liabilities and stockholders' equity / member's interest	3,857,641	3,787,333
Common Class A
Stockholders' equity / Member's interest
Common stock	1,117	1,104
Common Class B
Stockholders' equity / Member's interest
Common stock	0	0
Summit Materials, LLC
Current assets:
Cash and cash equivalents	128,508	383,556
Accounts receivable, net	214,518	198,330
Costs and estimated earnings in excess of billings	18,602	9,512
Inventories	213,851	184,439
Other current assets	16,061	7,764
Total current assets	591,540	783,601
Property, plant and equipment	1,780,132	1,615,424
Goodwill	1,193,028	1,037,320
Intangible assets	18,460	16,833
Other assets	50,084	51,063
Total assets	3,633,244	3,504,241
Current liabilities:
Current portion of debt	6,354	4,765
Current portion of acquisition-related liabilities	31,770	11,587
Accounts payable	109,008	100,637
Accrued expenses	100,029	116,274
Billings in excess of costs and estimated earnings	11,840	15,750
Total current liabilities	259,001	249,013
Long-term debt	1,807,502	1,810,833
Acquisition-related liabilities	45,354	52,239
Other noncurrent liabilities	135,956	100,562
Total liabilities	2,247,813	2,212,647
Commitments and contingencies (see note 16)
Stockholders' equity / Member's interest
Member's equity	1,396,241	1,359,760
Accumulated earnings (deficit)	12,806	(51,031)
Accumulated other comprehensive income	(23,616)	(17,135)
Total member's interest	1,385,431	1,291,594
Total liabilities and stockholders' equity / member's interest	$ 3,633,244	$ 3,504,241

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 29, 2018	Dec. 30, 2017
Common stock, shares issued (in shares)	115,094,445	114,040,214
Common Class A
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	111,658,927	110,350,594
Common stock, shares outstanding (in shares)	111,658,927	110,350,594
Common Class B
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	99	100
Common stock, shares outstanding (in shares)	99	100

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Revenue:
Product	$ 1,600,159	$ 1,449,936	$ 1,223,008
Service	309,099	302,473	265,266
Net revenue	1,909,258	1,752,409	1,488,274
Delivery and subcontract revenue	191,744	180,166	137,789
Total revenue	2,101,002	1,932,575	1,626,063
Cost of revenue (excluding items shown separately below):
Product	1,058,544	898,281	751,419
Service	225,491	203,330	182,584
Net cost of revenue	1,284,035	1,101,611	934,003
Delivery and subcontract cost	191,744	180,166	137,789
Total cost of revenue	1,475,779	1,281,777	1,071,792
General and administrative expenses	253,609	242,670	243,512
Depreciation, depletion, amortization and accretion	204,910	179,518	149,300
Transaction costs	4,238	7,733	6,797
Operating income	162,466	220,877	154,662
Interest expense	116,548	108,549	97,536
Loss on debt financings	149	4,815	0
Tax receivable agreement (benefit) expense	(22,684)	271,016	14,938
Gain on sale of business	(12,108)	0	0
Other (income) loss, net	(15,516)	(5,303)	1,361
Income (loss) from operations before taxes	96,077	(158,200)	40,827
Income tax expense (benefit)	59,747	(283,977)	(5,299)
Net income	36,330	125,777	46,126
Net (loss) income attributable to noncontrolling interest in subsidiaries	0	(27)	16
Net income attributable to Summit Holdings	2,424	3,974	9,327
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC	33,906	121,830	$ 36,783
Income per share of Class A common stock:
Basic (USD per share)			$ 0.52
Weighted average shares of Class A common stock:
Basic (in shares)			70,355,042
Summit Materials, LLC
Revenue:
Product	1,600,159	1,449,936	$ 1,223,008
Service	309,099	302,473	265,266
Net revenue	1,909,258	1,752,409	1,488,274
Delivery and subcontract revenue	191,744	180,166	137,789
Total revenue	2,101,002	1,932,575	1,626,063
Cost of revenue (excluding items shown separately below):
Product	1,058,544	898,281	751,419
Service	225,491	203,330	182,584
Net cost of revenue	1,284,035	1,101,611	934,003
Delivery and subcontract cost	191,744	180,166	137,789
Total cost of revenue	1,475,779	1,281,777	1,071,792
General and administrative expenses	253,609	242,670	243,512
Depreciation, depletion, amortization and accretion	204,910	179,518	149,300
Transaction costs	4,238	7,733	6,797
Operating income	162,466	220,877	154,662
Interest expense	115,831	107,655	96,483
Loss on debt financings	149	4,815	0
Gain on sale of business	(12,108)	0	0
Other (income) loss, net	(15,516)	(5,289)	1,374
Income (loss) from operations before taxes	74,110	113,696	56,805
Income tax expense (benefit)	10,273	(20,345)	(5,282)
Net income	63,837	134,041	62,087
Net (loss) income attributable to noncontrolling interest	0	(27)	16
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC	$ 63,837	$ 134,068	$ 62,071
Common Class A
Income per share of Class A common stock:
Basic (USD per share)	$ 0.30	$ 1.12	$ 0.52
Diluted (USD per share)	$ 0.30	$ 1.11	$ 0.52
Weighted average shares of Class A common stock:
Basic (in shares)	111,380,175	108,696,438	70,355,042
Diluted (in shares)	112,316,646	109,490,898	70,838,508

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Net income	$ 36,330	$ 125,777	$ 46,126
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	429	0
Postretirement liability adjustment	1,661	699	426
Foreign currency translation adjustment	(9,348)	7,768	2,125
Income (loss) on cash flow hedges	1,206	1,413	(1,529)
Less tax effect of other comprehensive income (loss) items	1,578	(288)	0
Other comprehensive (loss) income:	(4,903)	10,021	1,022
Comprehensive income	31,427	135,798	47,148
Less comprehensive (loss) income attributable to the noncontrolling interest in consolidated subsidiaries	0	(27)	16
Less comprehensive income attributable to Summit Holdings	2,226	4,360	9,803
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	29,201	131,465	37,329
Summit Materials, LLC
Net income	63,837	134,041	62,087
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	429	0
Postretirement liability adjustment	1,661	699	426
Foreign currency translation adjustment	(9,348)	7,768	2,125
Income (loss) on cash flow hedges	1,206	1,413	(1,529)
Other comprehensive (loss) income:	(6,481)	10,309	1,022
Comprehensive income	57,356	144,350	63,109
Less comprehensive (loss) income attributable to the noncontrolling interest in consolidated subsidiaries	0	(27)	16
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	$ 57,356	$ 144,377	$ 63,093

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Cash flow from operating activities:
Net income	$ 36,330	$ 125,777	$ 46,126
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	208,772	193,107	160,633
Share-based compensation expense	25,378	21,140	49,940
Net gain on asset disposals	(30,093)	(7,638)	(3,102)
Non-cash loss on debt financings	0	3,856	0
Change in deferred tax asset, net	57,490	(289,219)	(4,263)
Other	2,018	(2,359)	(1,282)
(Increase) decrease in operating assets, net of acquisitions and dispositions:
Accounts receivable, net	(5,796)	(3,720)	2,511
Inventories	(11,598)	(18,609)	(10,297)
Costs and estimated earnings in excess of billings	(8,702)	(1,825)	(2,684)
Other current assets	(7,159)	8,703	(5,518)
Other assets	(106)	(3,103)	(2,350)
(Decrease) increase in operating liabilities, net of acquisitions and dispositions:
Accounts payable	(13,403)	6,192	(5,751)
Accrued expenses	(16,544)	(7,006)	13,196
Billings in excess of costs and estimated earnings	(5,052)	109	700
Tax receivable agreement liability	(21,666)	273,194	58,145
Other liabilities	(501)	(6,416)	(51,141)
Net cash provided by operating activities	209,368	292,183	244,863
Cash flow from investing activities:
Acquisitions, net of cash acquired	(246,017)	(374,930)	(336,958)
Purchases of property, plant and equipment	(220,685)	(194,146)	(153,483)
Proceeds from the sale of property, plant and equipment	21,635	17,072	16,868
Proceeds from sale of business	21,564	0	0
Other	3,804	(471)	2,921
Net cash used for investing activities	(419,699)	(552,475)	(470,652)
Cash flow from financing activities:
Proceeds from equity offerings	0	237,600	0
Capital issuance costs	0	(627)	(136)
Proceeds from debt issuances	64,500	302,000	354,000
Debt issuance costs	(550)	(6,416)	(5,801)
Payments on debt	(85,042)	(16,438)	(120,702)
Purchase of noncontrolling interests	0	(532)	0
Payments on acquisition-related liabilities	(36,504)	(34,650)	(32,040)
Distributions from partnership	(69)	(1,974)	(13,034)
Proceeds from stock option exercises	15,615	21,661	440
Other	(1,943)	(869)	(20)
Net cash (used in) provided by financing activities	(43,993)	499,755	182,707
Impact of foreign currency on cash	(724)	701	69
Net (decrease) increase in cash	(255,048)	240,164	(43,013)
Cash and cash equivalents—beginning of period	383,556	143,392	186,405
Cash and cash equivalents—end of period	128,508	383,556	143,392
Summit Materials, LLC
Cash flow from operating activities:
Net income	63,837	134,041	62,087
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	208,055	192,213	159,579
Share-based compensation expense	25,378	21,140	49,940
Net gain on asset disposals	(30,093)	(7,638)	(3,102)
Non-cash loss on debt financings	0	3,856	0
Change in deferred tax asset, net	9,729	(23,070)	(8,572)
Other	2,018	(2,359)	(1,282)
(Increase) decrease in operating assets, net of acquisitions and dispositions:
Accounts receivable, net	(5,796)	(3,720)	2,511
Inventories	(11,598)	(18,609)	(10,297)
Costs and estimated earnings in excess of billings	(8,702)	(1,825)	(2,684)
Other current assets	(7,159)	8,703	(5,518)
Other assets	(106)	(3,103)	1,976
(Decrease) increase in operating liabilities, net of acquisitions and dispositions:
Accounts payable	(13,989)	8,040	(5,706)
Accrued expenses	(16,653)	(6,230)	12,064
Billings in excess of costs and estimated earnings	(5,052)	109	700
Other liabilities	(501)	(6,416)	(6,819)
Net cash provided by operating activities	209,368	295,132	244,877
Cash flow from investing activities:
Acquisitions, net of cash acquired	(246,017)	(374,930)	(336,958)
Purchases of property, plant and equipment	(220,685)	(194,146)	(153,483)
Proceeds from the sale of property, plant and equipment	21,635	17,072	16,868
Proceeds from sale of business	21,564	0	0
Other	3,804	(471)	2,921
Net cash used for investing activities	(419,699)	(552,475)	(470,652)
Cash flow from financing activities:
Capital contributions by member	15,615	304,541	27,377
Capital issuance costs	0	(627)	(136)
Proceeds from debt issuances	64,500	302,000	354,000
Debt issuance costs	(550)	(6,416)	(5,801)
Payments on debt	(85,042)	(16,438)	(120,702)
Purchase of noncontrolling interests	0	(532)	0
Payments on acquisition-related liabilities	(34,004)	(32,150)	(29,540)
Distributions from partnership	(2,569)	(51,986)	(42,192)
Other	(1,943)	(866)	(16)
Net cash (used in) provided by financing activities	(43,993)	497,526	182,990
Impact of foreign currency on cash	(724)	701	69
Net (decrease) increase in cash	(255,048)	240,884	(42,716)
Cash and cash equivalents—beginning of period	383,556	142,672	185,388
Cash and cash equivalents—end of period	$ 128,508	$ 383,556	$ 142,672

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity / Member's Interest and Redeemable Noncontrolling Interest - USD ($) $ in Thousands	Total	Common Class A	Common Class B	Noncontrolling Interest in subsidiaries	Accumulated Earnings/Deficit	Accumulated Other Comprehensive Income (Loss)	Common StockCommon Class A	Common StockCommon Class B	Additional Paid-in Capital	Noncontrolling Interest in Summit Inc.	Summit Materials, LLC	Summit Materials, LLCMembers' equity	Summit Materials, LLCAccumulated Earnings/Deficit	Summit Materials, LLCAccumulated Other Comprehensive Income (Loss)	Summit Materials, LLCNoncontrolling Interest in Summit Inc.
Beginning balance stockholders' equity at Jan. 02, 2016	$ 767,860			$ 1,362	$ 10,870	$ (2,795)	$ 497	$ 690	$ 619,003	$ 138,233
Beginning balance stockholders' equity (in shares) at Jan. 02, 2016							49,745,944	69,007,297
Beginning balance members' interest at Jan. 02, 2016											$ 778,292	$ 1,050,882	$ (245,486)	$ (28,466)	$ 1,362
Increase (Decrease) In Stockholders' Equity [Rollforward]
Net contributed capital											27,260	27,260
Net income (loss)	46,126			16	36,783					9,327	62,087		62,071		16
LP Unit exchanges (in shares)							45,124,528
LP Unit exchanges	0						$ 451		117,813	(118,264)
Other comprehensive income (loss), net of tax	1,022					546				476	1,022			1,022
Distributions											(42,192)	(42,192)
Stock option exercises (in shares)							24,354
Stock option exercises	440						$ 2		438
Class B share cancellation (in shares)								(69,007,197)
Class B share cancellation	0							$ (690)	690
Share-based compensation	49,940				(1,684)				51,624		49,940	51,624	(1,684)
Dividend (in shares)							1,135,692
Dividend	(4)				(26,941)		$ 11		27,047	(121)
Distributions from partnership	(13,034)									(13,034)
Shares redeemed to settle taxes and other (in shares)							2,704
Shares redeemed to settle taxes and other	7,689								7,689		(16)	(16)
Ending balance stockholders' equity at Dec. 31, 2016	$ 860,039			1,378	19,028	(2,249)	$ 961	$ 0	824,304	16,617
Ending balance stockholders' equity (in shares) at Dec. 31, 2016	102,705,575	97,554,278					96,033,222	100
Ending balance members' interest at Dec. 31, 2016											876,393	1,087,558	(185,099)	(27,444)	1,378
Increase (Decrease) In Stockholders' Equity [Rollforward]
Net contributed capital											303,914	303,914
Net income (loss)	$ 125,777			(27)	121,830					3,974	134,041		134,068		(27)
Issuance of Shares (in shares)	10,000,000	10,000,000					10,000,000
Issuance of Shares	$ 236,971						$ 100		238,367	(1,496)
LP Unit exchanges (in shares)		1,461,677					1,461,677
LP Unit exchanges	0						$ 15		4,159	(4,174)
Other comprehensive income (loss), net of tax	10,021					9,635				386	10,309			10,309
Distributions											(51,986)	(51,986)
Stock option exercises (in shares)							1,203,121
Stock option exercises	21,661						$ 12		21,649
Share-based compensation	21,140								21,140		21,140	21,140
Purchase of noncontrolling interest	(1,148)			$ (1,148)							(1,148)				(1,148)
Dividend (in shares)							1,521,056
Dividend	(2)				(45,025)		$ 15		45,163	(155)
Distributions from partnership	$ (1,974)									(1,974)
Shares redeemed to settle taxes and other (in shares)	1,334,639	1,334,639		(203,000)			131,518
Shares redeemed to settle taxes and other	$ (764)						$ 1		(562)		(1,069)	(866)			(203)
Ending balance stockholders' equity at Dec. 30, 2017	$ 1,271,721			$ 0	95,833	7,386	$ 1,104	$ 0	1,154,220	13,178
Ending balance stockholders' equity (in shares) at Dec. 30, 2017	114,040,214	110,350,594	100				110,350,594	100
Ending balance members' interest at Dec. 30, 2017											1,291,594	1,359,760	(51,031)	(17,135)	0
Increase (Decrease) In Stockholders' Equity [Rollforward]
Net contributed capital											15,615	15,615
Net income (loss)	$ 36,330				33,906					2,424	63,837		63,837
Issuance of Shares (in shares)		254,102
LP Unit exchanges (in shares)	1,054,231	1,054,231					254,102
LP Unit exchanges	$ 0						$ 2		929	(931)
Other comprehensive income (loss), net of tax	(4,903)					(4,705)				(198)	(6,481)			(6,481)
Distributions											(2,569)	(2,569)
Stock option exercises (in shares)							863,898
Stock option exercises	15,616						$ 9		15,607
Share-based compensation	25,378								25,378		25,378	25,378
Distributions from partnership	(69)									(69)
Shares redeemed to settle taxes and other (in shares)							190,333	(1)
Shares redeemed to settle taxes and other	(1,928)						$ 2		(1,930)		(1,943)	(1,943)
Ending balance stockholders' equity at Dec. 29, 2018	$ 1,342,145			$ 0	$ 129,739	$ 2,681	$ 1,117	$ 0	$ 1,194,204	$ 14,404
Ending balance stockholders' equity (in shares) at Dec. 29, 2018	115,094,445	111,658,927	99				111,658,927	99
Ending balance members' interest at Dec. 29, 2018											$ 1,385,431	$ 1,396,241	$ 12,806	$ (23,616)	$ 0

Summary of Organization and Sig

Summary of Organization and Significant Accounting Policies	12 Months Ended
	Dec. 29, 2018
Company Information
Summary of Organization and Significant Accounting Policies	Summary of Organization and Significant Accounting Policies Summit Materials, Inc. (“Summit Inc.” and, together with its subsidiaries, the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments. Substantially all of the Company’s products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions and to cyclical changes in construction spending, among other factors. On September 23, 2014, Summit Inc. was formed as a Delaware corporation to be a holding company. Its sole material asset is a controlling equity interest in Summit Materials Holdings L.P. (“Summit Holdings”). Pursuant to a reorganization into a holding company structure (the “Reorganization”) consummated in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries. Summit Inc. owns the majority of the partnership interests of Summit Holdings (see note 11, Stockholders’ Equity). Summit Materials, LLC (“Summit LLC”) an indirect wholly owned subsidiary of Summit Holdings, conducts the majority of our operations. Continental Cement Company, L.L.C. (“Continental Cement”) is also a wholly owned subsidiary of Summit LLC. Summit Materials Finance Corp. (“Summit Finance”), an indirect wholly owned subsidiary of Summit LLC, has jointly issued our Senior Notes as described below. Principles of Consolidation —The consolidated financial statements include the accounts of Summit Inc. and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. As a result of the Reorganization, Summit Holdings became a variable interest entity over which Summit Inc. has 100% voting power and control and for which Summit Inc. has the obligation to absorb losses and the right to receive benefits. 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 last occurred in 2015. For a summary of the changes in Summit Inc.’s ownership of Summit Holdings, see Note 11, Stockholders’ Equity. The Company attributes consolidated stockholders’ equity and net income separately to the controlling and noncontrolling interests. The Company accounts for investments in entities for which it has an ownership of 20% to 50% using the equity method of accounting. Use of Estimates —Preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, the tax receivable agreement (“TRA”) liability, 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. 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 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas 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 a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in 2018, 2017 or 2016. Accounts Receivable —Accounts receivable are stated at the amount management expects to collect from outstanding balances. Management provides for probable uncollectible amounts through a charge to earnings and a credit to a valuation allowance based on its assessment of the collectability of individual accounts. In establishing the allowance, management considers historical losses adjusted to take into account current market conditions and its customers’ financial condition, the amount of receivables in dispute, the current receivables aging and current payment terms. Balances that remain outstanding after reasonable collection efforts are exercised are written off through a charge to the valuation allowance. The balances billed but not paid by customers, pursuant to retainage provisions included in contracts, are generally due upon completion of the contracts. Revenue Recognition —We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental. Products We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped. Aggregates and cement products are sold point-of-sale through purchase orders. When the product is sold on account, collectability typically occurs 30 to 60 days after the sale. Revenue is recognized when cash is received from the customer at the point of sale or when the products are delivered or collected on site. There are no other timing implications that will create a contract asset or liability, and contract modifications are unlikely given the timing and nature of the transaction. Material sales are likely to have multiple performance obligations if the product is sold with delivery. In these instances, delivery most often occurs on the same day as the control of the product transfers to the customer. As a result, even in the case of multiple performance obligations, the performance obligations are satisfied concurrently and revenue is recognized simultaneously. Services We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants, and underground storage space rental. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations. Collectability of service contracts is due reasonably after certain milestones in the contract are performed. Milestones vary by project, but are typically calculated using monthly progress based on the percentage of completion or a customer’s engineer review of progress. The majority of the time, collection occurs within 90 days of billing and cash is received within the same fiscal year as services performed. On most projects, the customer will withhold a portion of the invoice for retainage, which may last longer than a year depending on the job. Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified. The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the year ended December 29, 2018 . We recognize claims when the amount of the claim can be estimated reliably and its realization is probable. In evaluating these criteria, we consider the contractual basis for the claim, the cause of any additional costs incurred, the reasonableness of those costs and the objective evidence available to support the claim. When the contract includes variable consideration, we estimate the amount of consideration to which we will be entitled in exchange for transferring the promised goods or services to a customer. The amount of estimated variable consideration included in the transaction price is the amount for which it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Types of variable consideration include, but are not limited to, liquidated damages and other performance penalties and production and placement bonuses. The majority of contract modifications relate to the original contract and are often an extension of the original performance obligation. Predominately, modifications are not distinct from the terms in the original contract; therefore, they are considered part of a single performance obligation. We account for the modification using a cumulative catch-up adjustment. However, there are instances where goods or services in a modification are distinct from those transferred prior to the modification. In these situations, we account for the modifications as either a separate contract or prospectively depending on the facts and circumstances of the modification. Generally, construction contracts contain mobilization costs which are categorized as costs to fulfill a contract. These costs are excluded from any measure of progress toward contract fulfillment. These costs do not result in the transfer of control of a good or service to the customer and are amortized over the life of the contract. Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis. Inventories —Inventories consist of stone that has been removed from quarries and processed for future sale, cement, raw materials and finished concrete blocks. Inventories are valued at the lower of cost or market and are accounted for on a first-in first-out basis or an average cost basis. If items become obsolete or otherwise unusable or if quantities exceed what is projected to be sold within a reasonable period of time, they will be charged to costs of production in the period that the items are designated as obsolete or excess inventory. Stripping costs are costs of removing overburden and waste material to access aggregate materials and are expensed as incurred. Property, Plant and Equipment, net —Property, plant and equipment are recorded at cost, less accumulated depreciation, depletion and amortization. Expenditures for additions and improvements that significantly add to the productive capacity or extend the useful life of an asset are capitalized. Repair and maintenance costs that do not substantially expand productive capacity or extend the life of property, plant and equipment are expensed as incurred. Landfill airspace is included in property, plant and equipment at cost and is amortized based on the portion of the airspace used during the period compared to the gross estimated value of available airspace, which is updated periodically as circumstances dictate. Management reassesses the landfill airspace capacity with any changes in value recorded in cost of revenue. Capitalized landfill costs include expenditures for the acquisition of land and related airspace, engineering and permitting costs, cell construction costs and direct site improvement costs. Upon disposal of an asset, the cost and related accumulated depreciation are removed from the Company’s accounts and any gain or loss is included in general and administrative expenses. The Company reviews the carrying value of property, plant and equipment for impairment whenever events or circumstances indicate that the carrying value of an asset may not be recoverable from the estimated future cash flows expected to result from its use and eventual disposition. Such indicators may include, among others, deterioration in general economic conditions, adverse changes in the markets in which an entity operates, increases in input costs that have a negative effect on earnings and cash flows or a trend of negative or declining cash flows over multiple periods. Property, plant and equipment is tested for impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. As a result, the property, plant and equipment impairment test is at a significantly lower level than the level at which goodwill is tested for impairment. In markets where the Company does not produce downstream products, such as ready-mix concrete, asphalt paving mix and paving and related services, the lowest level of largely independent identifiable cash flows is at the individual aggregates operation or a group of aggregates operations collectively serving a local market or the cement operations. Conversely, in vertically-integrated markets, the cash flows of the downstream and upstream businesses are not largely independently identifiable and the vertically-integrated operations are considered the lowest level of largely independent identifiable cash flows. Accrued Mining and Landfill Reclamation —The mining reclamation reserve and financial commitments for landfill closure and post-closure activities are based on management’s estimate of future cost requirements to reclaim property at both currently operating and closed sites. Estimates of these obligations have been developed based on management’s interpretation of current requirements and proposed regulatory changes and are intended to approximate fair value. Costs are estimated in current dollars, inflated until the expected time of payment, and then discounted back to present value using a credit-adjusted, risk-free rate on obligations of similar maturity, adjusted to reflect the Company’s credit rating. Changes in the credit-adjusted, risk-free rate do not change recorded liabilities. However, subsequent increases in the recognized obligations are measured using a current credit-adjusted, risk-free rate. Decreases in the recognized obligations are measured at the initial credit-adjusted, risk-free rate. Significant changes in inflation rates or the amount or timing of future cost estimates typically result in both (1) a current adjustment to the recorded liability (and corresponding adjustment to the asset) and (2) a change in accretion of the liability and depreciation of the asset to be recorded prospectively over the remaining capacity of the unmined quarry or landfill. Goodwill —Goodwill represents the purchase price paid in excess of the fair value of net tangible and intangible assets acquired. Goodwill recorded in connection with the Company’s acquisitions is primarily attributable to the expected profitability, assembled workforces of the acquired businesses and the synergies expected to arise after the Company’s acquisition of those businesses. Goodwill is not amortized, but is tested annually for impairment as of the first day of the fourth quarter and at any time that events or circumstances indicate that goodwill may be impaired. A qualitative approach may first be applied to determine whether it is more likely than not that the estimated fair value of a reporting unit is less than its carrying amount. If, as a result of the qualitative assessment, it is determined that an impairment is more likely than not, the two-step quantitative impairment test is then performed, otherwise further analysis is not required. The two-step impairment test first identifies potential goodwill impairment for each reporting unit and then, if necessary, measures the amount of the impairment loss. Income Taxes —Summit Inc. is a corporation subject to income taxes in the United States. Certain subsidiaries, including Summit Holdings, or subsidiary groups of the Company are taxable separate from Summit Inc. The provisions, or Summit Inc.’s proportional share of the provision, are included in the Company’s consolidated financial statements. The Company’s deferred income tax assets and liabilities are computed for differences between the tax basis and financial statement amounts that will result in taxable or deductible amounts in the future. The computed deferred balances are based on enacted tax laws and applicable rates for the periods in which the differences are expected to affect taxable income. A valuation allowance is recognized for deferred tax assets if it is more likely than not that some portion or all of the net deferred tax assets will not be realized. In making such a determination, all available positive and negative evidence is considered, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines it would be able to realize its deferred tax assets for which a valuation allowance had been recorded then an adjustment would be made to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company evaluates the tax positions taken on income tax returns that remain open and positions expected to be taken on the current year tax returns to identify uncertain tax positions. Unrecognized tax benefits on uncertain tax positions are recorded on the basis of a two-step process in which (1) the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, the largest amount of tax benefit that is more than 50 percent likely to be realized is recognized. Interest and penalties related to unrecognized tax benefits are recorded in income tax benefit. Tax Receivable Agreement — When Summit Inc. purchases LP Units for cash or LP Units are exchanged for shares of Class A common stock, this results in increases in Summit Inc.’s share of the tax basis of the tangible and intangible assets, which increases the tax depreciation and amortization deductions that otherwise would not have been available to Summit Inc. These increases in tax basis and tax depreciation and amortization deductions are expected to reduce the amount of cash taxes that we would otherwise be required to pay in the future. Prior to our IPO, we entered into a TRA with the pre-IPO owners that require us to pay the pre-IPO owners 85% of the amount of cash savings, if any, in U.S. federal, state, and local income tax that we actually realize as a result of these exchanges. These benefits include (1) increases in the tax basis of tangible and intangible assets of Summit Holdings and certain other tax benefits related to entering into the TRA, (2) tax benefits attributable to payments under the TRA, or (3) under certain circumstances such as an early termination of the TRA, we are deemed to realize, as a result of the increases in tax basis in connection with exchanges by the pre-IPO owners described above and certain other tax benefits attributable to payments under the TRA. As noted above, we periodically evaluate the realizability of the deferred tax assets resulting from the exchange of LP Units for Class A common stock. If the deferred tax assets are determined to be realizable, we then assess whether payment of amounts under the TRA have become probable. If so, we record a TRA liability equal to 85% of such deferred tax assets. In subsequent periods, we assess the realizability of all of our deferred tax assets subject to the TRA. Should we determine a deferred tax asset with a valuation allowance is realizable in a subsequent period, the related valuation allowance will be released and consideration of a corresponding TRA liability will be assessed. The realizability of deferred tax assets, including those subject to the TRA, is dependent upon the generation of future taxable income during the periods in which those deferred tax assets become deductible and consideration of prudent and feasible tax-planning strategies. The measurement of the TRA liability is accounted for as a contingent liability. Therefore, once we determine that a payment to a pre-IPO owner has become probable and can be estimated, the estimate of payment will be accrued. Earnings per Share— The Company computes basic earnings per share attributable to stockholders by dividing income attributable to Summit Inc. by the weighted-average shares of Class A common stock 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 stock has no economic value, those shares are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the shares of Class A common stock are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic earnings per share. New Accounting Standards — In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers , which 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. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. We adopted this new standard in January 2018 using the modified retrospective approach. The adoption of this new ASU did not have a material impact on our consolidated financial results. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will result in lessees recognizing most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018, are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have compiled our leases, and currently estimate that we will record additional right of use assets and liabilities of approximately $30 to $40 million beginning in 2019. We plan to adopt this ASU, as amended, using the modified retrospective approach. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business, which narrows the definition of a business. This ASU provides a screen to determine whether a group of assets constitutes a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated as acquisitions. If the screen is not met, this ASU (1) requires that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create an output and (2) removes the evaluation of whether a market participant could replace missing elements. Although outputs are not required for a set to be a business, outputs generally are a key element of a business; therefore, the FASB has developed more stringent criteria for sets without outputs. We adopted this ASU beginning in 2018. The adoption of this ASU did not have a material impact on the consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements.
Summit Materials, LLC
Company Information
Summary of Organization and Significant Accounting Policies	Summary of Organization and Significant Accounting Policies Summit Materials, LLC (“Summit LLC” and, together with its subsidiaries, the “Company”) is a vertically-integrated, construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments. Substantially all of the Company’s products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions and to cyclical changes in construction spending, among other factors. Summit LLC is a wholly owned indirect subsidiary of Summit Materials Holdings L.P. (“Summit Holdings”), whose primary owner is Summit Materials, Inc. (“Summit Inc.”). Summit Inc. was formed as a Delaware corporation on September 23, 2014. Its sole material asset is a controlling equity interest in Summit Holdings. Pursuant to a reorganization into a holding company structure (the “Reorganization”) in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries, including Summit LLC. Principles of Consolidation –The consolidated financial statements include the accounts of Summit LLC and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. The Company attributes consolidated member’s interest and net income separately to the controlling and noncontrolling interests. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the initial public offering (“IPO”) and concurrent purchase of the noncontrolling interests Continental Cement Company, L.L.C. (“Continental Cement”), a 30% redeemable ownership in Continental Cement. The Company accounts for investments in entities for which it has an ownership of 20% to 50% using the equity method of accounting. In the fourth quarter of 2017, we purchased the remaining noncontrolling interest in Ohio Valley Asphalt, LLC. 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 occurred in 2015. Use of Estimates — Preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, valuation of deferred tax assets, 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. 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 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas 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 a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in 2018 , 2017 or 2016 . Accounts Receivable —Accounts receivable are stated at the amount management expects to collect from outstanding balances. Management provides for probable uncollectible amounts through a charge to earnings and a credit to a valuation allowance based on its assessment of the collectability of individual accounts. In establishing the allowance, management considers historical losses adjusted to take into account current market conditions and its customers’ financial condition, the amount of receivables in dispute, the current receivables aging and current payment terms. Balances that remain outstanding after reasonable collection efforts are exercised are written off through a charge to the valuation allowance. The balances billed but not paid by customers, pursuant to retainage provisions included in contracts, are generally due upon completion of the contracts. Revenue Recognition —We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental. Products We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped. Aggregates and cement products are sold point-of-sale through purchase orders. When the product is sold on account, collectability typically occurs 30 to 60 days after the sale. Revenue is recognized when cash is received from the customer at the point of sale or when the products are delivered or collected on site. There are no other timing implications that will create a contract asset or liability, and contract modifications are unlikely given the timing and nature of the transaction. Material sales are likely to have multiple performance obligations if the product is sold with delivery. In these instances, delivery most often occurs on the same day as the control of the product transfers to the customer. As a result, even in the case of multiple performance obligations, the performance obligations are satisfied concurrently and revenue is recognized simultaneously. Services We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants, and underground storage space rental. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations. Collectability of service contracts is due reasonably after certain milestones in the contract are performed. Milestones vary by project, but are typically calculated using monthly progress based on the percentage of completion or a customer’s engineer review of progress. The majority of the time, collection occurs within 90 days of billing and cash is received within the same fiscal year as services performed. On most projects, the customer will withhold a portion of the invoice for retainage, which may last longer than a year depending on the job. Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified. The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the year ended December 29, 2018 . We recognize claims when the amount of the claim can be estimated reliably and its realization is probable. In evaluating these criteria, we consider the contractual basis for the claim, the cause of any additional costs incurred, the reasonableness of those costs and the objective evidence available to support the claim. When the contract includes variable consideration, we estimate the amount of consideration to which we will be entitled in exchange for transferring the promised goods or services to a customer. The amount of estimated variable consideration included in the transaction price is the amount for which it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Types of variable consideration include, but are not limited to, liquidated damages and other performance penalties and production and placement bonuses. The majority of contract modifications relate to the original contract and are often an extension of the original performance obligation. Predominately, modifications are not distinct from the terms in the original contract; therefore, they are considered part of a single performance obligation. We account for the modification using a cumulative catch-up adjustment. However, there are instances where goods or services in a modification are distinct from those transferred prior to the modification. In these situations, we account for the modifications as either a separate contract or prospectively depending on the facts and circumstances of the modification. Generally, construction contracts contain mobilization costs which are categorized as costs to fulfill a contract. These costs are excluded from any measure of progress toward contract fulfillment. These costs do not result in the transfer of control of a good or service to the customer and are amortized over the life of the contract. Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis. Inventories —Inventories consist of stone that has been removed from quarries and processed for future sale, cement, raw materials and finished concrete blocks. Inventories are valued at the lower of cost or market and are accounted for on a first-in first-out basis or an average cost basis. If items become obsolete or otherwise unusable or if quantities exceed what is projected to be sold within a reasonable period of time, they will be charged to costs of production in the period that the items are designated as obsolete or excess inventory. Stripping costs are costs of removing overburden and waste material to access aggregate materials and are expensed as incurred. Property, Plant and Equipment, net —Property, plant and equipment are recorded at cost, less accumulated depreciation, depletion and amortization. Expenditures for additions and improvements that significantly add to the productive capacity or extend the useful life of an asset are capitalized. Repair and maintenance costs that do not substantially expand productive capacity or extend the life of property, plant and equipment are expensed as incurred. Landfill airspace is included in property, plant and equipment at cost and is amortized based on the portion of the airspace used during the period compared to the gross estimated value of available airspace, which is updated periodically as circumstances dictate. Management reassesses the landfill airspace capacity with any changes in value recorded in cost of revenue. Capitalized landfill costs include expenditures for the acquisition of land and related airspace, engineering and permitting costs, cell construction costs and direct site improvement costs. Upon disposal of an asset, the cost and related accumulated depreciation are removed from the Company’s accounts and any gain or loss is included in general and administrative expenses. The Company reviews the carrying value of property, plant and equipment for impairment whenever events or circumstances indicate that the carrying value of an asset may not be recoverable from the estimated future cash flows expected to result from its use and eventual disposition. Such indicators may include, among others, deterioration in general economic conditions, adverse changes in the markets in which an entity operates, increases in input costs that have a negative effect on earnings and cash flows or a trend of negative or declining cash flows over multiple periods. Property, plant and equipment is tested for impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. As a result, the property, plant and equipment impairment test is at a significantly lower level than the level at which goodwill is tested for impairment. In markets where the Company does not produce downstream products, such as ready-mix concrete, asphalt paving mix and paving and related services, the lowest level of largely independent identifiable cash flows is at the individual aggregates operation or a group of aggregates operations collectively serving a local market or the cement operations. Conversely, in vertically-integrated markets, the cash flows of the downstream and upstream businesses are not largely independently identifiable and the vertically-integrated operations are considered the lowest level of largely independent identifiable cash flows. Accrued Mining and Landfill Reclamation —The mining reclamation reserve and financial commitments for landfill closure and post-closure activities are based on management’s estimate of future cost requirements to reclaim property at both currently operating and closed sites. Estimates of these obligations have been developed based on management’s interpretation of current requirements and proposed regulatory changes and are intended to approximate fair value. Costs are estimated in current dollars, inflated until the expected time of payment, and then discounted back to present value using a credit-adjusted, risk-free rate on obligations of similar maturity, adjusted to reflect the Company’s credit rating. Changes in the credit-adjusted, risk-free rate do not change recorded liabilities. However, subsequent increases in the recognized obligations are measured using a current credit-adjusted, risk-free rate. Decreases in the recognized obligations are measured at the initial credit-adjusted, risk-free rate. Significant changes in inflation rates or the amount or timing of future cost estimates typically result in both (1) a current adjustment to the recorded liability (and corresponding adjustment to the asset) and (2) a change in accretion of the liability and depreciation of the asset to be recorded prospectively over the remaining capacity of the unmined quarry or landfill. Goodwill —Goodwill represents the purchase price paid in excess of the fair value of net tangible and intangible assets acquired. Goodwill recorded in connection with the Company’s acquisitions is primarily attributable to the expected profitability, assembled workforces of the acquired businesses and the synergies expected to arise after the Company’s acquisition of those businesses. Goodwill is not amortized, but is tested annually for impairment as of the first day of the fourth quarter and at any time that events or circumstances indicate that goodwill may be impaired. A qualitative approach may first be applied to determine whether it is more likely than not that the estimated fair value of a reporting unit is less than its carrying amount. If, as a result of the qualitative assessment, it is determined that an impairment is more likely than not, the two-step quantitative impairment test is then performed, otherwise further analysis is not required. The two-step impairment test first identifies potential goodwill impairment for each reporting unit and then, if necessary, measures the amount of the impairment loss. Income Taxes —As a limited liability company, the Company’s federal and state income tax attributes are generally passed to its member. However, certain subsidiaries, or subsidiary groups, of the Company are taxable entities subject to income taxes in the United States and Canada, the provisions for which are included in the consolidated financial statements. Significant judgments and estimates are required in the determination of the consolidated income tax expense. The Company’s deferred income tax assets and liabilities are computed for differences between the tax basis and financial statement amounts that will result in taxable or deductible amounts in the future. The computed deferred balances are based on enacted tax laws and applicable rates for the periods in which the differences are expected to affect taxable income. A valuation allowance is recognized for deferred tax assets if it is more likely than not that some portion or all of the net deferred tax assets will not be realized. In making such a determination, all available positive and negative evidence is considered, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines it would be able to realize its deferred tax assets for which a valuation allowance had been recorded then an adjustment would be made to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company evaluates the tax positions taken on income tax returns that remain open and positions expected to be taken on the current year tax returns to identify uncertain tax positions. Unrecognized tax benefits on uncertain tax positions are recorded on the basis of a two-step process in which (1) the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, the largest amount of tax benefit that is more than 50 percent likely to be realized is recognized. Interest and penalties related to unrecognized tax benefits are recorded in income tax benefit. New Accounting Standards — In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers , which 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. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. We adopted this new standard in January 2018 using the modified retrospective approach. The adoption of this new ASU did not have a material impact on our consolidated financial results. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will result in lessees recognizing most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018, are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have compiled our leases, and currently estimate that we will record additional right of use assets and liabilities of approximately $30 to $40 million beginning in 2019. We plan to adopt this ASU, as amended, using the modified retrospective approach. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business, which narrows the definition of a business. This ASU provides a screen to determine whether a group of assets constitutes a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated as acquisitions. If the screen is not met, this ASU (1) requires that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create an output and (2) removes the evaluation of whether a market participant could replace missing elements. Although outputs are not required for a set to be a business, outputs generally are a key element of a business; therefore, the FASB has developed more stringent criteria for sets without outputs. We adopted this ASU beginning in 2018. The adoption of this ASU did not have a material impact on the consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 29, 2018
Acquisitions	Acquisitions The Company has completed numerous acquisitions since its formation, which have been financed through a combination of debt and equity funding. The operations of each acquisition have been included in the Company’s consolidated results of operations since the respective closing dates of the acquisitions. The Company measures all assets acquired and liabilities assumed at their acquisition-date fair value. The following table summarizes the Company’s acquisitions by region and year: 2018 2017 2016 West 5 6 3 East (1) 7 8 5 Cement — — 1 ______________________ (1) In addition, the Company acquired certain assets of a small ready-mix concrete operation in the second quarter of 2018. The purchase price allocation for certain 2018 acquisitions has not yet been finalized due to the recent timing of the acquisitions and status of the valuation of property, plant and equipment, among other items. The table below summarizes aggregated information regarding the fair values of the assets acquired and liabilities assumed as of the respective acquisition dates. Information related to the 2018 acquisitions is shown on an aggregated basis as the acquisitions were not material individually, or collectively. 2018 2017 Financial assets $ 14,769 $ 31,615 Inventories 18,313 8,300 Property, plant and equipment 124,957 160,975 Intangible assets 3,175 161 Other assets 1,539 4,200 Financial liabilities (13,529 ) (15,501 ) Other long-term liabilities (8,125 ) (17,610 ) Net assets acquired 141,099 172,140 Goodwill 154,120 247,536 Purchase price 295,219 419,676 Acquisition-related liabilities (49,202 ) (43,452 ) Other — (1,294 ) Net cash paid for acquisitions $ 246,017 $ 374,930 Acquisition-Related Liabilities —A number of acquisition-related liabilities have been recorded subject to terms in the relevant purchase agreements, including deferred consideration and noncompete payments. Noncompete payments have been accrued where certain former owners of newly acquired companies have entered into standard noncompete arrangements. Subject to terms and conditions stated in these noncompete agreements, payments are generally made over a five-year period. Deferred consideration is purchase price consideration paid in the future as agreed to in the purchase agreement and is not contingent on future events. Deferred consideration is generally scheduled to be paid in years ranging from five to 20 years in annual installments. The remaining payments due under these noncompete and deferred consideration agreements are as follows: 2019 $ 32,960 2020 31,745 2021 9,705 2022 3,411 2023 2,657 Thereafter 9,640 Total scheduled payments 90,118 Present value adjustments (12,949 ) Total noncompete obligations and deferred consideration $ 77,169 Accretion on the deferred consideration and noncompete obligations is recorded in interest expense.
Summit Materials, LLC
Acquisitions	Acquisitions The Company has completed numerous acquisitions since its formation, which have been financed through a combination of debt and equity funding. The operations of each acquisition have been included in the Company’s consolidated results of operations since the respective closing dates of the acquisitions. The Company measures all assets acquired and liabilities assumed at their acquisition-date fair value. The following table summarizes the Company’s acquisitions by region and year: 2018 2017 2016 West 5 6 3 East (1) 7 8 5 Cement — — 1 ______________________ (1) In addition, the Company acquired certain assets of a small ready-mix concrete operation in the second quarter of 2018. The purchase price allocation for certain 2018 acquisitions has not yet been finalized due to the recent timing of the acquisitions and status of the valuation of property, plant and equipment, among other items. The table below summarizes aggregated information regarding the fair values of the assets acquired and liabilities assumed as of the respective acquisition dates. Information related to the 2018 acquisitions is shown on an aggregated basis as the acquisitions were not material individually, or collectively. 2018 2017 Financial assets $ 14,769 $ 31,615 Inventories 18,313 8,300 Property, plant and equipment 124,957 160,975 Intangible assets 3,175 161 Other assets 1,539 4,200 Financial liabilities (13,529 ) (15,501 ) Other long-term liabilities (8,125 ) (17,610 ) Net assets acquired 141,099 172,140 Goodwill 154,120 247,536 Purchase price 295,219 419,676 Acquisition-related liabilities (49,202 ) (43,452 ) Other — (1,294 ) Net cash paid for acquisitions $ 246,017 $ 374,930 Acquisition-Related Liabilities —A number of acquisition-related liabilities have been recorded subject to terms in the relevant purchase agreements, including deferred consideration and noncompete payments. Noncompete payments have been accrued where certain former owners of newly acquired companies have entered into standard noncompete arrangements. Subject to terms and conditions stated in these noncompete agreements, payments are generally made over a five-year period. Deferred consideration is purchase price consideration paid in the future as agreed to in the purchase agreement and is not contingent on future events. Deferred consideration is generally scheduled to be paid in years ranging from five to 20 years in annual installments. The remaining payments due under these noncompete and deferred consideration agreements are as follows: 2019 $ 30,460 2020 29,245 2021 7,205 2022 3,411 2023 2,657 Thereafter 9,640 Total scheduled payments 82,618 Present value adjustments (12,063 ) Total noncompete obligations and deferred consideration $ 70,555 Accretion on the deferred consideration and noncompete obligations is recorded in interest expense.

Goodwill

Goodwill	12 Months Ended
	Dec. 29, 2018
Goodwill	Goodwill As of December 29, 2018 , the Company had 12 reporting units with goodwill for which the annual goodwill impairment test was completed. We perform the annual impairment test on the first day of the fourth quarter each year. We initially perform a qualitative analysis. As a result of this analysis, it was determined that it is more likely than not that the fair value of four reporting units were greater than its carrying value. For the remaining reporting units we perform a two-step quantitative analysis. Step 1 of that analysis compares the estimated the fair value of the reporting units using an income approach (i.e., a discounted cash flow technique) and a market approach to the carrying value of the reporting unit. If the estimated fair value exceeds its carrying value, the goodwill of the reporting unit is not considered impaired. If the carrying value of the reporting unit exceeds its fair value, we proceed to the second step to measure the amount of potential impairment loss. Based on this analysis, it was determined that the reporting units’ fair values were greater than their carrying values and no impairment charges were recognized in 2018 . The accumulated impairment charges recognized in periods prior to 2016 totaled $68.2 million . These estimates of a reporting unit’s fair value involve significant management estimates and assumptions, including but not limited to sales prices of similar assets, assumptions related to future profitability, cash flows, and discount rates. These estimates are based upon historical trends, management’s knowledge and experience and overall economic factors, including projections of future earnings potential. Developing discounted future cash flow estimates in applying the income approach required management to evaluate its intermediate to longer-term strategies, including, but not limited to, estimates about revenue growth, operating margins, capital requirements, inflation and working capital management. The development of appropriate rates to discount the estimated future cash flows required the selection of risk premiums, which can materially affect the present value of estimated future cash flows. In addition to the financial impact of Hurricane Harvey, our operations in Austin continue to be pressured by aggressive competition, which has further impacted volumes and pricing. We expect the Austin market to continue to grow, and the Texas Department of Transportation to invest in infrastructure projects in that area. The Austin reporting unit has approximately $18 million of goodwill as of December 29, 2018 , which we continue to believe is realizable. The key assumptions around the realizability analysis are revenue growth, as well as the discount rate of 10% . Our discount rate came under pressure in the fourth quarter of 2018 due to decreases in the market price of our Class A common stock. We will continue to monitor whether an event indicates the carrying value of the Austin based reporting unit may be impaired. The following table presents goodwill by reportable segments and in total: West East Cement Total Balance, December 31, 2016 $ 334,257 $ 243,417 $ 204,538 $ 782,212 Acquisitions 187,883 61,957 118 249,958 Foreign currency translation adjustments 4,150 — — 4,150 Balance, December 30, 2017 $ 526,290 $ 305,374 $ 204,656 $ 1,036,320 Acquisitions (1) 59,148 101,431 — 160,579 Foreign currency translation adjustments (4,871 ) — — (4,871 ) Balance, December 29, 2018 $ 580,567 $ 406,805 $ 204,656 $ 1,192,028 ______________________ (1) Reflects goodwill from 2018 acquisitions and working capital adjustments from prior year acquisitions.
Summit Materials, LLC
Goodwill	Goodwill As of December 29, 2018 , the Company had 12 reporting units with goodwill for which the annual goodwill impairment test was completed. We perform the annual impairment test on the first day of the fourth quarter each year. We initially perform a qualitative analysis. As a result of this analysis, it was determined that it is more likely than not that the fair value of four reporting units were greater than its carrying value. For the remaining reporting units we perform a two-step quantitative analysis. Step 1 of that analysis compares the estimated the fair value of the reporting units using an income approach (i.e., a discounted cash flow technique) and a market approach to the carrying value of the reporting unit. If the estimated fair value exceeds its carrying value, the goodwill of the reporting unit is not considered impaired. If the carrying value of the reporting unit exceeds its fair value, we proceed to the second step to measure the amount of potential impairment loss. Based on this analysis, it was determined that the reporting units’ fair values were greater than their carrying values and no impairment charges were recognized in 2018 . The accumulated impairment charges recognized in periods prior to 2016 totaled $68.2 million . These estimates of a reporting unit’s fair value involve significant management estimates and assumptions, including but not limited to sales prices of similar assets, assumptions related to future profitability, cash flows, and discount rates. These estimates are based upon historical trends, management’s knowledge and experience and overall economic factors, including projections of future earnings potential. Developing discounted future cash flow estimates in applying the income approach required management to evaluate its intermediate to longer-term strategies, including, but not limited to, estimates about revenue growth, operating margins, capital requirements, inflation and working capital management. The development of appropriate rates to discount the estimated future cash flows required the selection of risk premiums, which can materially affect the present value of estimated future cash flows. In addition to the financial impact of Hurricane Harvey, our operations in Austin continue to be pressured by aggressive competition, which has further impacted volumes and pricing. We expect the Austin market to continue to grow, and the Texas Department of Transportation to invest in infrastructure projects in that area. The Austin reporting unit has approximately $18 million of goodwill as of December 29, 2018, which we continue to believe is realizable. The key assumptions around the realizability analysis are revenue growth, as well as the discount rate of 10% . Our discount rate came under pressure in the fourth quarter of 2018 due to decreases in the market price of our Class A common stock. We will continue to monitor whether an event indicates the carrying value of the Austin based reporting unit may be impaired. The following table presents goodwill by reportable segments and in total: West East Cement Total Balance, December 31, 2016 $ 334,257 $ 243,417 $ 204,538 $ 782,212 Acquisitions 188,883 61,957 118 250,958 Foreign currency translation adjustments 4,150 — — 4,150 Balance, December 30, 2017 $ 527,290 $ 305,374 $ 204,656 $ 1,037,320 Acquisitions (1) 59,148 101,431 — 160,579 Foreign currency translation adjustments (4,871 ) — — (4,871 ) Balance, December 29, 2018 $ 581,567 $ 406,805 $ 204,656 $ 1,193,028 ______________________ (1) Reflects goodwill from 2018 acquisitions and working capital adjustments from prior year acquisitions.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 29, 2018
Revenue from External Customer [Line Items]
Revenue Recognition	Revenue Recognition We derive our revenue predominantly by selling construction materials, products and providing paving and related services. Construction materials consist of aggregates and cement. Products consist of related downstream products, including ready-mix concrete, asphalt paving mix and concrete products. Paving and related service revenue is generated primarily from the asphalt paving services that we provide. Revenue by product for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 consisted of the following: 2018 2017 2016 Revenue by product*: Aggregates $ 373,824 $ 313,383 $ 264,609 Cement 258,876 282,041 250,349 Ready-mix concrete 584,114 492,302 395,917 Asphalt 301,247 285,653 239,419 Paving and related services 379,540 371,763 304,041 Other 203,401 187,433 171,728 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Revenue from the liquid asphalt terminals is included in asphalt revenue. The following table outlines the significant changes in contract assets and contract liability balances from December 30, 2017 to December 29, 2018 . Also included in the table is the net change in the estimate as a percentage of aggregate revenue for such contracts: Costs and estimated Billings in excess earnings in of costs and excess of billings estimated earnings Balance—December 30, 2017 $ 9,512 $ 15,750 Changes in revenue billed, contract price or cost estimates 8,702 (5,052 ) Acquisitions 483 1,179 Other (95 ) (37 ) Balance—December 29, 2018 $ 18,602 $ 11,840 Accounts receivable, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Trade accounts receivable $ 157,601 $ 137,696 Construction contract receivables 47,994 49,832 Retention receivables 15,010 14,973 Receivables from related parties 629 468 Accounts receivable 221,234 202,969 Less: Allowance for doubtful accounts (6,716 ) (4,639 ) Accounts receivable, net $ 214,518 $ 198,330 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 generally billed and collected within one year .
Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenue Recognition	Revenue Recognition We derive our revenue predominantly by selling construction materials, products and providing paving and related services. Construction materials consist of aggregates and cement. Products consist of related downstream products, including ready-mix concrete, asphalt paving mix and concrete products. Paving and related service revenue is generated primarily from the asphalt paving services that we provide. Revenue by product for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 consisted of the following: 2018 2017 2016 Revenue by product*: Aggregates $ 373,824 $ 313,383 $ 264,609 Cement 258,876 282,041 250,349 Ready-mix concrete 584,114 492,302 395,917 Asphalt 301,247 285,653 239,419 Paving and related services 379,540 371,763 304,041 Other 203,401 187,433 171,728 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ *Revenue from the liquid asphalt terminals is included in asphalt revenue. The following table outlines the significant changes in contract assets and contract liability balances from December 30, 2017 to December 29, 2018 . Also included in the table is the net change in the estimate as a percentage of aggregate revenue for such contracts: Costs and estimated Billings in excess earnings in of costs and excess of billings estimated earnings Balance—December 30, 2017 $ 9,512 $ 15,750 Changes in revenue billed, contract price or cost estimates 8,702 (5,052 ) Acquisitions 483 1,179 Other (95 ) (37 ) Balance—December 29, 2018 $ 18,602 $ 11,840 Accounts receivable, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Trade accounts receivable $ 157,601 $ 137,696 Construction contract receivables 47,994 49,832 Retention receivables 15,010 14,973 Receivables from related parties 629 468 Accounts receivable 221,234 202,969 Less: Allowance for doubtful accounts (6,716 ) (4,639 ) Accounts receivable, net $ 214,518 $ 198,330 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 generally billed and collected within one year .

Inventories

Inventories	12 Months Ended
	Dec. 29, 2018
Inventory [Line Items]
Inventories	Inventories Inventories consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Aggregate stockpiles $ 151,300 $ 126,791 Finished goods 34,993 34,667 Work in process 7,478 7,729 Raw materials 20,080 15,252 Total $ 213,851 $ 184,439
Summit Materials, LLC
Inventory [Line Items]
Inventories	Inventories Inventories consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Aggregate stockpiles $ 151,300 $ 126,791 Finished goods 34,993 34,667 Work in process 7,478 7,729 Raw materials 20,080 15,252 Total $ 213,851 $ 184,439

Property, Plant and Equipment,

Property, Plant and Equipment, net and Intangibles, net	12 Months Ended
	Dec. 29, 2018
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, net and Intangibles, net	Property, Plant and Equipment, net and Intangibles, net Property, plant and equipment, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Land (mineral bearing) and asset retirement costs $ 323,553 $ 274,083 Land (non-mineral bearing) 184,029 168,501 Buildings and improvements 173,559 170,615 Plants, machinery and equipment 1,239,793 1,068,007 Mobile equipment and barges 468,313 391,256 Truck and auto fleet 51,938 47,270 Landfill airspace and improvements 49,754 49,480 Office equipment 39,794 33,314 Construction in progress 43,650 44,739 Property, plant and equipment 2,574,383 2,247,265 Less accumulated depreciation, depletion and amortization (794,251 ) (631,841 ) Property, plant and equipment, net $ 1,780,132 $ 1,615,424 Depreciation on property, plant and equipment, including assets subject to capital leases, is generally computed on a straight-line basis. Depletion of mineral reserves is computed based on the portion of the reserves used during the period compared to the gross estimated value of proven and probable reserves, which is updated periodically as circumstances dictate. Leasehold improvements are amortized on a straight-line basis over the lesser of the asset’s useful life or the remaining lease term. The estimated useful lives are generally as follows: Buildings and improvements 10 - 30 years Plant, machinery and equipment 15 - 20 years Office equipment 3 - 7 years Truck and auto fleet 5 - 8 years Mobile equipment and barges 6 - 8 years Landfill airspace and improvements 10 - 30 years Other 4 - 20 years Depreciation, depletion and amortization expense of property, plant and equipment was $199.6 million , $174.4 million and $144.2 million in the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. Property, plant and equipment at December 29, 2018 and December 30, 2017 included $67.7 million and $51.2 million , respectively, of capital leases for certain equipment and a building with accumulated amortization of $19.3 million and $18.5 million , respectively. The equipment leases generally have terms of less than five years and the building lease had an original term of 30 years . Approximately $15.6 million and $19.3 million of the future obligations associated with the capital leases are included in accrued expenses as of December 29, 2018 and December 30, 2017 , respectively, and the present value of the remaining capital lease payments, $33.6 million and $16.4 million , respectively, is included in other noncurrent liabilities on the consolidated balance sheets. Future minimum rental commitments under long-term capital leases are $17.9 million , $13.9 million , $15.3 million , $3.0 million , and $1.0 million for the years ended 2019, 2020, 2021, 2022 and 2023, respectively. Assets are assessed for impairment charges when identified for disposition. The net gain from asset dispositions recognized in general and administrative expenses in fiscal years 2018 , 2017 and 2016 was $12.6 million , $7.5 million and $6.8 million , respectively. No material impairment charges have been recognized on assets held for use in fiscal 2018 , 2017 or 2016 . The losses are commonly a result of the cash flows expected from selling the asset being less than the expected cash flows that could be generated from holding the asset for use. Intangible Assets —The Company’s intangible assets are primarily composed of lease agreements and reserve rights. The assets related to lease agreements reflect the submarket royalty rates paid under agreements, primarily, for extracting aggregates. The values were determined as of the respective acquisition dates by a comparison of market-royalty rates to contract-royalty rates. The reserve rights relate to aggregate reserves to which the Company has the rights of ownership, but do not own the reserves. The intangible assets are amortized on a straight-line basis over the lives of the leases. The following table shows intangible assets by type and in total: December 29, 2018 December 30, 2017 Gross Net Gross Net Carrying Accumulated Carrying Carrying Accumulated Carrying Amount Amortization Amount Amount Amortization Amount Leases $ 19,064 $ (5,259 ) $ 13,805 $ 15,888 $ (4,178 ) $ 11,710 Reserve rights 6,234 (1,940 ) 4,294 6,234 (1,625 ) 4,609 Trade names 1,000 (858 ) 142 1,000 (758 ) 242 Other 409 (190 ) 219 409 (137 ) 272 Total intangible assets $ 26,707 $ (8,247 ) $ 18,460 $ 23,531 $ (6,698 ) $ 16,833 Amortization expense in fiscal 2018 , 2017 and 2016 was $1.5 million , $1.3 million and $2.6 million , respectively. The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows: 2019 $ 1,588 2020 1,510 2021 1,475 2022 1,482 2023 1,349 Thereafter 11,056 Total $ 18,460
Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, net and Intangibles, net	Property, Plant and Equipment, net and Intangibles, net Property, plant and equipment, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Land (mineral bearing) and asset retirement costs $ 323,553 $ 274,083 Land (non-mineral bearing) 184,029 168,501 Buildings and improvements 173,559 170,615 Plants, machinery and equipment 1,239,793 1,068,007 Mobile equipment and barges 468,313 391,256 Truck and auto fleet 51,938 47,270 Landfill airspace and improvements 49,754 49,480 Office equipment 39,794 33,314 Construction in progress 43,650 44,739 Property, plant and equipment 2,574,383 2,247,265 Less accumulated depreciation, depletion and amortization (794,251 ) (631,841 ) Property, plant and equipment, net $ 1,780,132 $ 1,615,424 Depreciation on property, plant and equipment, including assets subject to capital leases, is generally computed on a straight-line basis. Depletion of mineral reserves is computed based on the portion of the reserves used during the period compared to the gross estimated value of proven and probable reserves, which is updated periodically as circumstances dictate. Leasehold improvements are amortized on a straight-line basis over the lesser of the asset’s useful life or the remaining lease term. The estimated useful lives are generally as follows: Buildings and improvements 10-30 years Plant, machinery and equipment 15 - 20 years Office equipment 3-7 years Truck and auto fleet 5-8 years Mobile equipment and barges 6-8 years Landfill airspace and improvements 10-30 years Other 4-20 years Depreciation, depletion and amortization expense of property, plant and equipment was $199.6 million , $174.4 million and $144.2 million in the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. Property, plant and equipment at December 29, 2018 and December 30, 2017 included $67.7 million and $51.2 million , respectively, of capital leases for certain equipment and a building with accumulated amortization of $19.3 million and $18.5 million , respectively. The equipment leases generally have terms of less than five years and the building lease had an original term of 30 years . Approximately $15.6 million and $19.3 million of the future obligations associated with the capital leases are included in accrued expenses as of December 29, 2018 and December 30, 2017 , respectively, and the present value of the remaining capital lease payments, $33.6 million and $16.4 million , respectively, is included in other noncurrent liabilities on the consolidated balance sheets. Future minimum rental commitments under long-term capital leases are $17.9 million , $13.9 million , $15.3 million , $3.0 million , and $1.0 million for the years ended 2019, 2020, 2021, 2022 and 2023, respectively. Assets are assessed for impairment charges when identified for disposition. The net gain from asset dispositions recognized in general and administrative expenses in fiscal years 2018 , 2017 and 2016 was $12.6 million , $7.5 million and $6.8 million , respectively. No material impairment charges have been recognized on assets held for use in fiscal 2018 , 2017 or 2016 . The losses are commonly a result of the cash flows expected from selling the asset being less than the expected cash flows that could be generated from holding the asset for use. Intangible Assets —The Company’s intangible assets are primarily composed of lease agreements and reserve rights. The assets related to lease agreements reflect the submarket royalty rates paid under agreements, primarily, for extracting aggregates. The values were determined as of the respective acquisition dates by a comparison of market-royalty rates to contract-royalty rates. The reserve rights relate to aggregate reserves to which the Company has the rights of ownership, but do not own the reserves. The intangible assets are amortized on a straight-line basis over the lives of the leases. The following table shows intangible assets by type and in total: December 29, 2018 December 30, 2017 Gross Net Gross Net Carrying Accumulated Carrying Carrying Accumulated Carrying Amount Amortization Amount Amount Amortization Amount Leases $ 19,064 $ (5,259 ) $ 13,805 $ 15,888 $ (4,178 ) $ 11,710 Reserve rights 6,234 (1,940 ) 4,294 6,234 (1,625 ) 4,609 Trade names 1,000 (858 ) 142 1,000 (758 ) 242 Other 409 (190 ) 219 409 (137 ) 272 Total intangible assets $ 26,707 $ (8,247 ) $ 18,460 $ 23,531 $ (6,698 ) $ 16,833 Amortization expense in fiscal 2018 , 2017 and 2016 was $1.5 million , $1.3 million and $2.6 million , respectively. The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows: 2019 $ 1,588 2020 1,510 2021 1,475 2022 1,482 2023 1,349 Thereafter 11,056 Total $ 18,460

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 29, 2018
Schedule Of Accrued Expenses [Line Items]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Interest $ 26,223 $ 24,095 Payroll and benefits 15,952 33,915 Capital lease obligations 15,557 19,276 Insurance 13,625 11,455 Non-income taxes 7,442 7,236 Professional fees 1,408 1,717 Other (1) 20,284 18,935 Total $ 100,491 $ 116,629 ______________________ (1) Consists primarily of subcontractor and working capital settlement accruals and deferred revenue.
Summit Materials, LLC
Schedule Of Accrued Expenses [Line Items]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Interest $ 26,223 $ 24,095 Payroll and benefits 15,952 33,915 Capital lease obligations 15,557 19,276 Insurance 13,625 11,455 Non-income taxes 7,674 7,467 Professional fees 1,408 1,717 Other (1) 19,590 18,349 Total $ 100,029 $ 116,274 ______________________ (1) Consists primarily of subcontractor and working capital settlement accruals and deferred revenue.

Debt

Debt	12 Months Ended
	Dec. 29, 2018
Debt	Debt Debt consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Term Loan, due 2024: $630.6 million and $635.4 million, net of $1.3 million and $1.6 million discount at December 29, 2018 and December 30, 2017, respectively $ 629,268 $ 633,805 8 1/2% Senior Notes, due 2022 250,000 250,000 6 1/8% Senior Notes, due 2023: $650.0 million, net of $1.1 million and $1.4 million discount at December 29, 2018 and December 30, 2017, respectively 648,891 648,650 5 1/8% Senior Notes, due 2025 300,000 300,000 Total 1,828,159 1,832,455 Current portion of long-term debt 6,354 4,765 Long-term debt $ 1,821,805 $ 1,827,690 The contractual payments of long-term debt, including current maturities, for the five years subsequent to December 29, 2018 , are as follows: 2019 $ 6,354 2020 7,942 2021 6,354 2022 256,354 2023 656,354 Thereafter 897,253 Total 1,830,611 Less: Original issue net discount (2,452 ) Less: Capitalized loan costs (14,303 ) Total debt $ 1,813,856 Senior Notes — On June 1, 2017, Summit LLC and Summit Finance (together, the “Issuers”) issued $300 million of 5 1⁄8% senior notes due June 1, 2025 (the “2025 Notes”). The 2025 Notes were issued at 100% of their par value with proceeds of $295.4 million , net of related fees and expenses. The 2025 Notes were issued under an indenture dated June 1, 2017 (as amended and supplemented, the “2017 Indenture”). The 2017 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 its assets, enter inter certain transactions with affiliates, and designate subsidiaries as unrestricted subsidiaries. The 2017 Indenture also contains customary events of default. Interest on the 2025 Notes is payable semi-annually on June 1 and December 1 of each year commencing on December 1, 2017. In 2016, the Issuers issued $250.0 million of 8.5% senior notes due April 15, 2022 (the “2022 Notes”). The 2022 Notes were issued at 100% of their par value with proceeds of $246.3 million , net of related fees and expenses. The proceeds from the sale of the 2022 Notes were used to fund the acquisition of Boxley Materials Company, replenish cash used for the acquisition of American Materials Company and pay expenses incurred in connection with these acquisitions. The 2022 Notes were issued under an indenture dated March 8, 2016, the terms of which are generally consistent with the 2017 Indenture. Interest on the 2022 Notes is payable semi-annually in arrears on April 15 and October 15 of each year. In 2015, the Issuers issued $650 million of 6.125% senior notes due July 2023 (the “2023 Notes” and collectively with the 2022 Notes and the 2025 Notes, the “Senior Notes”). Of the aggregate $650.0 million of 2023 Notes, $350.0 million were issued at par and $300.0 million were issued at 99.375% of par. The 2023 Notes were issued under an indenture dated July 8, 2015, the terms of which are generally consistent with the 2017 Indenture. Interest on the 2023 Notes is payable semi-annually in arrears on January 15 and July 15 of each year. In April, August and November 2015, $288.2 million , $183.0 million and $153.8 million , respectively, in aggregate principal amount of the then outstanding 10 1/2% senior notes due January 31, 2020 (the “2020 Notes”) were redeemed at a price equal to par plus an applicable premium and the indenture under which the 2020 Notes were issued was satisfied and discharged. As a result of the redemptions, net charges of $56.5 million were recognized for the year ended December 31, 2016 . The fees included $66.6 million for the applicable prepayment premium and $11.9 million for the write-off of deferred financing fees, partially offset by $22.0 million of net benefit from the write-off of the original issuance net premium. As of December 29, 2018 and December 30, 2017 , the Company was in compliance with all financial covenants under the applicable indentures. Senior Secured Credit Facilities — Summit LLC has credit facilities that provide for term loans in an aggregate amount of $650.0 million and revolving credit commitments in an aggregate amount of $235.0 million (the “Senior Secured Credit Facilities”). Under the Senior Secured Credit Facilities, required principal repayments of 0.25% of the refinanced aggregate amount of term debt are due on the last business day of each March, June, September and December, commencing with the March 2018 payment. The unpaid principal balance is due in full on the maturity date, which is November 21, 2024. On January 19, 2017, Summit LLC entered into Amendment No. 1 (“Amendment No. 1”) to the credit agreement governing the Senior Secured Credit Facilities (the “Credit Agreement”), which, among other things, reduced the applicable margin in respect of then outstanding $640.3 million principal amount of term loans thereunder. All other material terms and provisions remain substantially identical to the terms and provisions in place immediately prior to the effectiveness of Amendment No. 1. On November 21, 2017, Summit LLC entered into Amendment No. 2 to the Credit Agreement, which, among other things, extended the maturity date from 2022 to 2024 and reduced the applicable margin in respect of the $635.4 million outstanding principal amount of term loans thereunder. On May 22, 2018, Summit LLC entered into Amendment No. 3 to the Credit Agreement, which, among other things, reduced the applicable margin in respect of the $633.8 million outstanding principal amount of term loans thereunder. 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 2.25% 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 3.25% for LIBOR rate loans. There were no outstanding borrowings under the revolving credit facility as of December 29, 2018 or December 30, 2017 . As of December 29, 2018 , we had remaining borrowing capacity of $219.6 million under the revolving credit facility, which is net of $15.4 million of outstanding letters of credit. The outstanding letters of credit are renewed annually and support required bonding on construction projects and the Company’s insurance liabilities. Summit LLC’s Consolidated First Lien Net Leverage Ratio, as such term is defined in the Credit Agreement, should be no greater than 4.75 :1.0 as of each quarter-end. As of December 29, 2018 and December 30, 2017 , Summit LLC was in compliance with all financial covenants under the Credit Agreement. Summit LLC’s wholly-owned domestic subsidiary companies, 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. The following table presents the activity for the deferred financing fees for the years ended December 29, 2018 and December 30, 2017 : Deferred financing fees Balance—December 31, 2016 $ 18,290 Loan origination fees 6,416 Amortization (3,990 ) Write off of deferred financing fees (1,683 ) Balance—December 30, 2017 $ 19,033 Loan origination fees 550 Amortization (4,108 ) Balance—December 29, 2018 $ 15,475 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 that subsidiary. There were no amounts outstanding under this agreement as of December 29, 2018 or December 30, 2017 .
Summit Materials, LLC
Debt	Debt Debt consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Term Loan, due 2024: $630.6 million and $635.4 million, net of $1.3 million and $1.6 million discount at December 29, 2018 and December 30, 2017, respectively $ 629,268 $ 633,805 8 1/2% Senior Notes, due 2022 250,000 250,000 6 1/8% Senior Notes, due 2023: $650.0 million, net of $1.1 million and $1.4 million discount at December 29, 2018 and December 30, 2017, respectively 648,891 648,650 5 1/8% Senior Notes, due 2025 300,000 300,000 Total 1,828,159 1,832,455 Current portion of long-term debt 6,354 4,765 Long-term debt $ 1,821,805 $ 1,827,690 The contractual payments of long-term debt, including current maturities, for the five years subsequent to December 29, 2018 , are as follows: 2019 $ 6,354 2020 7,942 2021 6,354 2022 256,354 2023 656,354 Thereafter 897,253 Total 1,830,611 Less: Original issue net discount (2,452 ) Less: Capitalized loan costs (14,303 ) Total debt $ 1,813,856 Senior Notes — On June 1, 2017, Summit LLC and Summit Materials Finance Corp., an indirect wholly-owned subsidiary of Summit LLC ("Finance Corp." and with Summit LLC, the “Issuers”) issued $300.0 million of 5.125% senior notes due June 1, 2025 (the “2025 Notes”). The 2025 Notes were issued at 100.0% of their par value with proceeds of $295.4 million , net of related fees and expenses. The 2025 Notes were issued under an indenture dated June 1, 2017 (as amended and supplemented, the “2017 Indenture”). The 2017 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 its assets, enter inter certain transactions with affiliates, and designate subsidiaries as unrestricted subsidiaries. The 2017 Indenture also contains customary events of default. Interest on the 2025 Notes is payable semi-annually on June 1 and December 1 of each year commencing on December 1, 2017. In 2016, the Issuers issued $250.0 million of 8.500% senior notes due April 15, 2022 (the “2022 Notes”). The 2022 Notes were issued at 100.0% of their par value with proceeds of $246.3 million , net of related fees and expenses. The proceeds from the sale of the 2022 Notes were used to fund the acquisition of Boxley Materials Company, replenish cash used for the acquisition of American Materials Company and pay expenses incurred in connection with these acquisitions. The 2022 Notes were issued under an indenture dated March 8, 2016, the terms of which are generally consistent with the 2017 Indenture. Interest on the 2022 Notes is payable semi-annually in arrears on April 15 and October 15 of each year. In 2015, the Issuers issued $650.0 million of 6.125% senior notes due July 2023 (the “2023 Notes” and collectively with the 2022 Notes and the 2025 Notes, the “Senior Notes”). Of the aggregate $650.0 million of 2023 Notes, $350.0 million were issued at par and $300.0 million were issued at 99.375% of par. The 2023 Notes were issued under an indenture dated July 8, 2015, the terms of which are generally consistent with the 2017 Indenture. Interest on the 2023 Notes is payable semi-annually in arrears on January 15 and July 15 of each year. In April, August and November 2015, $288.2 million , $183.0 million and $153.8 million , respectively, in aggregate principal amount of the then outstanding 10 1 / 2 % senior notes due January 31, 2020 (the “2020 Notes”) were redeemed at a price equal to par plus an applicable premium and the indenture under which the 2020 Notes were issued was satisfied and discharged. As a result of the redemptions, net charges of $56.5 million were recognized for the year ended December 31, 2016. The fees included $66.6 million for the applicable prepayment premium and $11.9 million for the write-off of deferred financing fees, partially offset by $22.0 million of net benefit from the write-off of the original issuance net premium. As of December 29, 2018 and December 30, 2017 , the Company was in compliance with all financial covenants under the applicable indentures. Senior Secured Credit Facilities — Summit LLC has credit facilities that provide for term loans in an aggregate amount of $650.0 million and revolving credit commitments in an aggregate amount of $235.0 million (the “Senior Secured Credit Facilities”). Under the Senior Secured Credit Facilities, required principal repayments of 0.25% of the refinanced aggregate amount of term debt are due on the last business day of each March, June, September and December, commencing with the March 2018 payment. The unpaid principal balance is due in full on the maturity date, which is November 21, 2024. On January 19, 2017, Summit LLC entered into Amendment No. 1 (“Amendment No. 1”) to the credit agreement governing the Senior Secured Credit Facilities (the “Credit Agreement”), which, among other things, reduced the applicable margin in respect of then outstanding $640.3 million principal amount of term loans thereunder. All other material terms and provisions remain substantially identical to the terms and provisions in place immediately prior to the effectiveness of Amendment No. 1. On November 21, 2017, Summit LLC entered into Amendment No. 2 to the Credit Agreement, which, among other things, extended the maturity date from 2022 to 2024 and reduced the applicable margin in respect of the $635.4 million outstanding principal amount of term loans thereunder. On May 22, 2018, Summit LLC entered into Amendment No. 3 to the Credit Agreement, which, among other things, reduced the applicable margin in respect of the $633.8 million outstanding principal amount of term loans thereunder. 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 2.25% 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 3.25% for LIBOR rate loans. There were no outstanding borrowings under the revolving credit facility as of December 29, 2018 or December 30, 2017 . As of December 29, 2018 , we had remaining borrowing capacity of $219.6 million under the revolving credit facility, which is net of $15.4 million of outstanding letters of credit. The outstanding letters of credit are renewed annually and support required bonding on construction projects and the Company’s insurance liabilities. Summit LLC’s Consolidated First Lien Net Leverage Ratio, as such term is defined in the Credit Agreement, should be no greater than 4.75 :1.0 as of each quarter-end. As of December 29, 2018 and December 30, 2017 , Summit LLC was in compliance with all financial covenants under the Credit Agreement. Summit LLC’s wholly-owned domestic subsidiary companies, 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. The following table presents the activity for the deferred financing fees for the years ended December 29, 2018 and December 30, 2017 : Deferred financing fees Balance—December 31, 2016 $ 18,290 Loan origination fees 6,416 Amortization (3,990 ) Write off of deferred financing fees (1,683 ) Balance—December 30, 2017 $ 19,033 Loan origination fees 550 Amortization (4,108 ) Balance—December 29, 2018 $ 15,475 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 that subsidiary. There were no amounts outstanding under this agreement as of December 29, 2018 or December 30, 2017 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 29, 2018
Income Taxes [Line Items]
Income Taxes	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 and a Canadian subsidiary. The tax attributes related to the limited liability companies are passed on to Summit Holdings and then to its partners, including Summit Inc. The tax attributes associated with the C corporation and Canadian subsidiaries are fully reflected in the Company’s consolidated financial statements. For the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , income taxes consisted of the following: 2018 2017 2016 Provision for income taxes: Current $ 463 $ 2,530 $ 2,835 Deferred 59,284 (286,507 ) (8,134 ) Income tax expense (benefit) $ 59,747 $ (283,977 ) $ (5,299 ) The effective tax rate on pre-tax income differs from the U.S. statutory rate of 21% , 35% , and 35% for 2018 , 2017 and 2016 , respectively, due to the following: 2018 2017 2016 Income tax expense (benefit) at federal statutory tax rate $ 20,177 $ (55,365 ) $ 14,290 Less: Income tax benefit at federal statutory tax rate for LLC entities (561 ) (2,123 ) (10,608 ) State and local income taxes 4,894 (5,209 ) 2,490 Permanent differences (5,537 ) (4,410 ) (5,902 ) Effective tax rate change 4,034 216,904 (1,432 ) Unrecognized tax benefits 22,663 — — Tax receivable agreement (benefit) expense (8,282 ) 104,804 5,228 Change in valuation allowance 17,592 (500,162 ) 239,008 Impact of LP Unit ownership change — (31,790 ) (252,456 ) Other 4,767 (6,626 ) 4,083 Income tax expense (benefit) $ 59,747 $ (283,977 ) $ (5,299 ) The following table summarizes the components of the net deferred income tax asset (liability) as December 29, 2018 and December 30, 2017 : 2018 2017 Deferred tax assets (liabilities): Net intangible assets $ 275,412 $ 316,950 Accelerated depreciation (185,020 ) (147,943 ) Net operating loss 143,234 94,751 Investment in limited partnership (29,981 ) (14,467 ) Mining reclamation reserve 1,600 1,239 Inventory purchase accounting adjustments — — Working capital (e.g., accrued compensation, prepaid assets) 36,932 35,237 Interest expense limitation carryforward 2,586 — Less valuation allowance (19,366 ) (1,675 ) Deferred tax assets 225,397 284,092 Less foreign deferred tax liability (included in other noncurrent liabilities) (5,133 ) (3,992 ) Net deferred tax asset $ 220,264 $ 280,100 As of December 29, 2018 , $379.4 million of our deferred tax assets subject to our TRA are included in the net intangible assets and the net operating loss line items above. Our income tax expense (benefit) was $59.7 million , $(284.0) million and $(5.3) million in the fiscal years ended 2018 , 2017 and 2016 , respectively. Our effective income tax rate in 2018 was impacted by the IRS interpretative guidance of TCJA, a change in state tax rates and a reduction in the amount of our TRA liability. We recorded an income tax benefit in fiscal 2017, primarily related to the release of the valuation allowance as discussed below, partially offset by charge related to the decrease in the federal statutory corporate tax rate. Our effective income tax rate in 2017 was higher as compared to 2016, primarily due to the benefit associated with the release of the valuation allowance discussed below, the accrual of the TRA expense, the statutory rate change referred to below and depletion in excess of U.S. GAAP depletion recognized in 2017. During the year ended 2016, our income tax benefit was $5.3 million . 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, as well as consideration of tax-planning strategies we may seek to utilize net operating loss carryforwards that begin to expire in 2030. Due to our limited operating history as of December 31, 2016, during which we incurred only a small amount of pre-tax income over the previous three years, as well as our acquisitive business strategy, after considering both positive and negative evidence, we concluded that it was not more likely than not that we would fully realize those deferred tax assets, and therefore recorded a partial valuation allowance against those deferred tax assets as of December 31, 2016. However, the amount of cumulative income increased significantly during the year ended December 30, 2017. As a result of this significant positive evidence, we determined that the deferred tax assets had become more likely than not of becoming realizable and therefore released the majority of the valuation allowance in the third quarter of 2017. The Company updated the analysis as of December 30, 2018, and adjusted the valuation allowance for interest expense carryforwards limited under TCJA. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“TCJA”) was enacted. Among other things, the TCJA, beginning January 1, 2018, reduced the federal statutory rate from 35% to 21% and extended bonus depreciation provisions. In addition, the TCJA prescribes the application of net operating loss carryforwards generated in 2018 and beyond will be limited, 100% asset expensing will be allowed through 2022 and begin to phase out in 2023, and the amount of interest expense we are able deduct may also be limited in future years. As a result of the enactment of TCJA and other state effective rate changes, we reduced the carrying value of our net deferred tax assets in the fourth quarter of 2017 by $216.9 million to reflect the revised federal statutory rate and other state statutory rates which will be in effect at the time those deferred tax assets are expected to be realized. The TCJA contains many provisions which continue to be clarified through new regulations. As permitted by Staff Accounting Bulletin 118 issued by the SEC on December 22, 2017, we completed our accounting of the impacts of the TCJA. We completed our analysis within 2018 consistent with the guidance of SAB 118 and any adjustments during the measurement period have been included in net earnings from continuing operations as an adjustment to income tax expense. We recorded additional tax expense of $17.6 million resulting from the IRS interpretative guidance of TCJA during the fourth quarter of 2018. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: Unrealized Tax Benefits Balance—December 30, 2017 $ — Additions based on tax position in 2018 22,663 Balance—December 29, 2018 $ 22,663 At December 29, 2018, there was $22.7 million of unrecognized tax benefits that if recognized would affect the annual effective tax rate. We did not recognize interest or penalties related to this amount as it is offset by other attributes. There were no uncertain tax positions for the years ended December 30, 2017 and December 31, 2016. Our net operating loss carryforward deferred tax assets begin to expire in 2030 and are expected to reverse before expiration. Therefore, we have not given consideration to any potential tax planning strategies as a source of future taxable income to monetize those net operating loss carryforwards. The Company will continue to monitor facts and circumstances, including our analysis of other sources of taxable income, in the reassessment of the likelihood that the tax benefit of our deferred tax assets will be realized. As of December 29, 2018 , Summit Inc. had federal net operating loss carryforwards of $664 million , which expire between 2030 and 2037. As of December 29, 2018, $322.5 million of our federal net operating losses were under the terms of our TRA. In addition, Summit Inc. has alternative minimum tax credits of $0.2 million as of December 29, 2018 , which do not expire. As of December 29, 2018 and December 30, 2017 , Summit Inc. had a valuation allowance on net deferred tax assets of $19.4 million and $1.7 million , respectively, where realization of our interest tax attributes and net operating losses are not more likely than not. 2018 2017 Valuation Allowance: Beginning balance $ (1,675 ) $ (502,839 ) Additional basis from exchanged LP Units (99 ) (31,790 ) Current year increases from operations (17,592 ) — Release of valuation allowance and other — 532,954 Ending balance $ (19,366 ) $ (1,675 ) Tax Receivable Agreement — During 2015, the Company entered into a TRA with the holders of LP Units and certain other pre-initial public offering 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. actually realizes (or, under certain circumstances such as an early termination of the TRA, is deemed to realize) as a result of increases in the tax basis of tangible and intangible assets of Summit Holdings and certain other tax benefits related to entering into the TRA, including tax benefits attributable to payments under the TRA. When LP Units are exchanged for an equal number of newly-issued shares of Summit Inc.’s Class A common stock, these exchanges result in new deferred tax assets. Using tax rates in effect as of each year end, $2.0 million , $12.4 million , and $422.5 million of deferred tax assets were created during the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively, when LP Units were exchanged for shares of Class A common stock. As noted above, when payments are made under the TRA, we expect the amount that is characterized as imputed interest will be limited under the proposed IRS regulations, and therefore the Company will not benefit from that deduction. Further, in 2018, we updated our estimate of the state income tax rate that will be in effect at the date the TRA payments are made. As a result of the updated state income tax rate, and the imputed interest limitation noted above, we have reduced our TRA liability by $22.7 million as of December 29, 2018. In the third quarter of 2017, as a result of the analysis of the realizability of our deferred tax assets as indicated above, we reduced the valuation allowance against our deferred tax assets, including those deferred tax assets subject to the TRA. Further, we determined the TRA liability to be probable of being payable and, as such, we recorded 85% of the deferred tax assets subject to the TRA, or $501.8 million , as TRA liability. Our TRA liability as of December 29, 2018 and December 30, 2017 was $310.4 million and $331.9 million , respectively, of which $0.7 million and $0.6 million was classified as accrued expenses, respectively. Tax Distributions – The holders of Summit Holdings’ LP Units, including Summit Inc., incur U.S. federal, state and local income taxes on their share of any taxable income of Summit Holdings. The limited partnership agreement of Summit Holdings provides for pro rata cash distributions (“tax distributions”) to the holders of the LP Units in an amount generally calculated to provide each holder of LP Units with sufficient cash to cover its tax liability in respect of the LP Units. In general, these tax distributions are computed based on Summit Holdings’ estimated taxable income allocated to Summit Inc. multiplied by an assumed tax rate equal to the highest effective marginal combined U.S. federal, state and local income tax rate applicable to a corporate resident in New York, New York. For the years ended December 29, 2018 and December 30, 2017 , Summit Holdings paid tax distributions totaling $0.1 million and $1.8 million , respectively, to holders of its LP Units, other than Summit Inc. C Corporation Subsidiaries — The effective income tax rate for the C corporations differ from the statutory federal rate primarily due to (1) tax depletion expense (benefit) in excess of the expense recorded under U.S. GAAP, (2) state income taxes and the effect of graduated tax rates, (3) various other items such as limitations on meals and entertainment and other costs and (4) unrecognized tax benefits. The effective income tax rate for the Canadian subsidiary is not significantly different from its historical effective tax rate. No material interest or penalties were recognized in income tax expense during the years ended December 29, 2018 , December 30, 2017 or December 31, 2016 . Tax years from 2014 to 2018 remain open and subject to audit by federal, Canadian, and state tax authorities.
Summit Materials, LLC
Income Taxes [Line Items]
Income Taxes	Income Taxes Summit LLC is a limited liability company and passes its tax attributes for federal and state tax purposes to its member and is generally not subject to federal or state income tax. However, certain subsidiaries, or subsidiary groups, file federal, state, and Canadian income tax returns due to their status as C corporations or laws within that jurisdiction. The provision for income taxes is primarily composed of federal, state and local income taxes for the subsidiary entities that have C corporation status. As of December 29, 2018 , the Company has recognized a reserve against the deferred tax assets for unrecognized tax benefits in the amount of $6.5 million . There were no unrecognized tax benefits recorded at December 30, 2017 . The Company records interest and penalties as a component of the income tax provision. No material interest or penalties were recognized in income tax expense during the years ended December 29, 2018 and December 30, 2017 . A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: Unrealized Tax Benefits Balance—December 30, 2017 $ — Additions based on tax position in 2018 6,487 Balance—December 29, 2018 $ 6,487 For the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , income taxes consisted of the following: 2018 2017 2016 Provision for income taxes: Current $ 463 $ 2,762 $ 2,835 Deferred 9,810 (23,107 ) (8,117 ) Income tax benefit $ 10,273 $ (20,345 ) $ (5,282 ) The effective tax rate on pre-tax income differs from the U.S. statutory rate of 21% , 35% and 35% for 2018, 2017 and 2016, respectively, due to the following: 2018 2017 2016 Income tax expense (benefit) at federal statutory tax rate $ 15,563 $ 39,797 $ 19,882 Less: Income tax benefit at federal statutory tax rate for LLC entities (13,863 ) (36,171 ) (21,042 ) State and local income taxes 1,614 1,751 1,279 Permanent differences (1,194 ) (630 ) (1,726 ) Effective tax rate change (1,148 ) (24,243 ) (1,432 ) Unrecognized tax benefits 6,487 — — Valuation allowance 2,586 — 148 Other 228 (849 ) (2,391 ) Income tax benefit $ 10,273 $ (20,345 ) $ (5,282 ) The following table summarizes the components of the net deferred income tax asset (liability) as December 29, 2018 and December 30, 2017 : 2018 2017 Deferred tax (liabilities) assets: Accelerated depreciation $ (57,437 ) $ (47,920 ) Net operating loss 22,915 20,671 Investment in limited partnership (16,591 ) (10,800 ) Net intangible assets (1,734 ) (1,256 ) Mining reclamation reserve 570 488 Working capital (e.g., accrued compensation, prepaid assets) 1,059 1,267 Interest expense limitation carryforward 2,586 — Net deferred tax liabilities (48,632 ) (37,550 ) Less valuation allowance (4,261 ) (1,675 ) Net deferred tax liability $ (52,893 ) $ (39,225 ) The net deferred income tax liability as of December 29, 2018 and December 30, 2017 , are included in other noncurrent liabilities on the consolidated balance sheets. As of December 29, 2018 , Summit LLC had federal net operating loss carryforwards of $118.5 million , which expire between 2030 and 2036. Summit LLC has alternative minimum tax credits of $0.2 million as of December 29, 2018 , which do not expire. Valuation Allowance —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 (including the effect of available carryback and carryforward periods) and tax-planning strategies. The deferred income tax asset related to net operating losses resides with two separate tax paying subsidiaries (or subsidiary groups) of Summit LLC. These tax payers have historically generated taxable income and forecast to continue generating taxable income; however, the use of a portion of the net operating may be limited. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“TCJA”) was enacted. Among other things, the TCJA, beginning January 1, 2018, reduced the federal statutory rate from 35% to 21% and extended bonus depreciation provisions. In addition, the TCJA prescribes the application of net operating loss carryforwards generated in 2018 and beyond will be limited, 100% asset expensing will be allowed through 2022 and begin to phase out in 2023, and the amount of interest expense we are able deduct may also be limited in future years. As permitted by Staff Accounting Bulletin 118 issued by the SEC on December 22, 2017, we completed our accounting of the impacts of the TCJA. The Company has completed its analysis within 2018 consistent with the guidance of SAB 118 and any adjustments during the measurement period have been included in net earnings from continuing operations as an adjustment to income tax expense. The Company recorded additional tax expense of $2.6 million resulting from the IRS interpretative guidance of TCJA during the fourth quarter of 2018. Therefore, a $4.3 million and $1.7 million , respectively, valuation allowance has been recorded on net deferred tax assets as of December 29, 2018 and December 30, 2017 , respectively, where realization of our interest tax attributes and net operating losses are not more likely than not. Tax years from 2014 to 2018 remain open and subject to audit by federal, Canadian, and state tax authorities. No income tax expense or benefit was recognized in other comprehensive loss in 2018, 2017 or 2016. Tax Distributions – The holders of Summit Holdings’ LP Units, including Summit Inc., incur U.S. federal, state and local income taxes on their share of any taxable income of Summit Holdings. The limited partnership agreement of Summit Holdings provides for pro rata cash distributions (“tax distributions”) to the holders of the LP Units in an amount generally calculated to provide each holder of LP Units with sufficient cash to cover its tax liability in respect of the LP Units. In general, these tax distributions are computed based on Summit Holdings’ estimated taxable income allocated to Summit Inc. multiplied by an assumed tax rate equal to the highest effective marginal combined U.S. federal, state and local income tax rate applicable to a corporate resident in New York, New York. In the years ended December 29, 2018 and December 30, 2017 , Summit LLC paid distributions to Summit Holdings totaling $0.1 million and $49.5 million , respectively, of which $0.1 million and $1.8 million , respectively, was distributed to Summit Holdings’ partners, other than Summit Inc., and $0 million and $47.5 million , respectively, was paid to Summit Inc.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 29, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per share is computed by dividing net earnings by the weighted average common shares outstanding and diluted net earnings is computed by dividing net earnings, adjusted for changes in the earnings allocated to Summit Inc. as a result of the assumed conversion of LP Units, by the weighted-average common shares outstanding assuming dilution. The following table shows the calculation of basic income per share: 2018 2017 2016 Net income attributable to Summit Inc. $ 33,906 $ 121,830 $ 36,783 Weighted average shares of Class A stock outstanding 111,380,175 108,696,438 70,355,042 Basic income per share $ 0.30 $ 1.12 $ 0.52 Net income (loss) attributable to Summit Inc. $ 33,906 $ 121,830 $ 36,783 Weighted average shares of Class A stock outstanding 111,380,175 108,696,438 70,355,042 Add: weighted average of LP Units — — — Add: stock options 282,329 308,355 140,142 Add: warrants 25,049 42,035 16,123 Add: restricted stock units 459,280 308,221 240,633 Add: performance stock units 169,813 135,849 86,568 Weighted average dilutive shares outstanding 112,316,646 109,490,898 70,838,508 Diluted earnings per share $ 0.30 $ 1.11 $ 0.52 Excluded from the above calculations were the shares noted below as they were antidilutive: 2018 2017 2016 Antidilutive shares: LP Units 3,512,669 4,371,705 32,327,907

Stockholder's Equity_Members' I

Stockholder's Equity/Members' Interest	12 Months Ended
	Dec. 29, 2018
Schedule of Capitalization, Equity [Line Items]
Stockholder's Equity	Stockholders’ Equity Our capital stock consists of 1.0 billion shares of $0.01 par value Class A common stock authorized, of which 110,350,594 shares were issued and outstanding as of December 29, 2018. We also have authorized 250 million shares of $0.01 par value Class B common stock, of which 99 shares were issued and outstanding as of December 29, 2018. The Class B common stock entitles holders thereof, who are also holders of LP Units, with a number of votes that is equal to the number of LP Units they hold. The Class B common stock does not participate in dividends and does not have any liquidation rights. Equity Offerings —On January 10, 2017, Summit Inc. raised $237.6 million , net of underwriting discounts, through the issuance of 10,000,000 shares of Class A common stock at a public offering price of $24.05 per share. Summit Inc. used these proceeds to purchase an equal number of LP Units. From time to time, limited partners of Summit Holdings exchange their LP Units for shares of Class A common stock of Summit Inc. The following table summarizes the changes in our ownership of Summit Holdings: Summit Inc. Shares (Class A) LP Units Total Summit Inc. Ownership Percentage Balance — December 31, 2016 97,554,278 5,151,297 102,705,575 95.0 % January 2017 public offering 10,000,000 — 10,000,000 Exchanges during period 1,461,677 (1,461,677 ) — Other equity transactions 1,334,639 — 1,334,639 Balance — December 30, 2017 110,350,594 3,689,620 114,040,214 96.8 % Exchanges during period 254,102 (254,102 ) — Other equity transactions 1,054,231 — 1,054,231 Balance — December 29, 2018 111,658,927 3,435,518 115,094,445 97.0 % Accumulated other comprehensive income (loss) - The changes in each component of accumulated other comprehensive income (loss) consisted of the following: Accumulated Foreign currency other Change in translation Cash flow hedge comprehensive retirement plans adjustments adjustments income (loss) Balance — December 31, 2016 $ 1,450 $ (3,106 ) $ (593 ) $ (2,249 ) Postretirement curtailment adjustment, net of tax 309 — — 309 Postretirement liability adjustment, net of tax 605 — — 605 Foreign currency translation adjustment, net of tax — 7,743 — 7,743 Income on cash flow hedges, net of tax — — 978 978 Balance — December 30, 2017 $ 2,364 $ 4,637 $ 385 $ 7,386 Postretirement liability adjustment, net of tax 1,209 — — 1,209 Foreign currency translation adjustment, net of tax — (6,784 ) — (6,784 ) Income on cash flow hedges, net of tax — — 870 870 Balance — December 29, 2018 $ 3,573 $ (2,147 ) $ 1,255 $ 2,681
Summit Materials, LLC
Schedule of Capitalization, Equity [Line Items]
Members' Interest	Members’ Interest Summit Inc.’s Equity Offerings — 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 % 2020 Notes; (ii) to purchase 71,428,571 Class B Units of Continental Cement; (iii) to pay a one-time termination fee of $13.8 million in connection with the termination of a transaction and management fee agreement with Blackstone Capital Partners V L.P.; and (iv) for general corporate purposes. The $288.2 million redemption of 2020 Notes was completed at a redemption price equal to par plus an applicable premium of $38.2 million plus $5.2 million of accrued and unpaid interest. On August 11, 2015, Summit Inc. raised $555.8 million , net of underwriting discounts, through the issuance of 22,425,000 shares of Class A common stock at a public offering price of $25.75 per share ("the August 2015 follow-on offering"). Summit Inc. used these proceeds to purchase 3.8 million newly-issued LP Units from Summit Holdings and 18,675,000 LP Units from certain pre-IPO owners, at a purchase price per LP Unit equal to the public offering price per share of Class A common stock, less underwriting discounts and commissions. Summit Holdings used the proceeds from the 3,750,000 newly-issued LP Units to pay the deferred purchase price of $80.0 million related to the July 17, 2015 acquisition of a cement plant and quarry in Davenport, Iowa, and seven cement terminals along the Mississippi River and for general corporate purposes. On January 10, 2017, Summit Inc. raised $237.6 million , net of underwriting discounts, through the issuance of 10,000,000 shares of Class A common stock at a public offering price of $24.05 per share. Summit Inc. used these proceeds to purchase an equal number of LP Units. 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 Inc. 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 shares of Summit Inc.’s Class A common stock 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. Prior to the March 17, 2015 purchase of the noncontrolling interest, the Company owned 100 Class A Units of Continental Cement, which represented an approximately 70% economic interest and had a preference in liquidation to the Class B Units. Continental Cement issued 100,000,000 Class B Units in May 2010, which remained outstanding until March 17, 2015 and represented an approximately 30% economic interest. Accumulated other comprehensive income (loss) - The changes in each component of accumulated other comprehensive income (loss) consisted of the following: Accumulated Foreign currency other Change in translation Cash flow hedge comprehensive retirement plans adjustments adjustments (loss) income Balance — December 31, 2016 $ (7,181 ) $ (17,790 ) $ (2,473 ) $ (27,444 ) Postretirement curtailment adjustment 429 — — 429 Postretirement liability adjustment 699 — — 699 Foreign currency translation adjustment — 7,768 — 7,768 Income on cash flow hedges — — 1,413 1,413 Balance — December 30, 2017 $ (6,053 ) $ (10,022 ) $ (1,060 ) $ (17,135 ) Postretirement liability adjustment 1,661 — — 1,661 Foreign currency translation adjustment — (9,348 ) — (9,348 ) Income on cash flow hedges — — 1,206 1,206 Balance — December 29, 2018 $ (4,392 ) $ (19,370 ) $ 146 $ (23,616 )

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 29, 2018
Schedule Of Cash Flow Supplemental [Line Items]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Supplemental cash flow information for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was as follows: 2018 2017 2016 Cash payments: Interest $ 103,250 $ 96,320 $ 82,540 Income taxes 3,340 1,711 2,645 Non cash financing activities: Purchase of noncontrolling interest $ — $ (716 ) $ — Stock Dividend — (45,023 ) (26,939 ) Exchange of LP Units to shares of Class A common stock 7,499 41,126 953,752
Summit Materials, LLC
Schedule Of Cash Flow Supplemental [Line Items]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Supplemental cash flow information for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was as follows: 2018 2017 2016 Cash payments: Interest $ 103,250 $ 96,320 $ 82,540 Income taxes 3,340 1,711 2,645 Non cash financing activities: Purchase of noncontrolling interest $ — $ (716 ) $ —

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 29, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-Based Compensation	Stock-Based Compensation Prior to the IPO and related Reorganization, the capital structure of Summit Holdings consisted of six different classes of limited partnership units, each of which was subject to unique distribution rights. In connection with the IPO and the related Reorganization, the limited partnership agreement of Summit Holdings was amended and restated to, among other things, modify its capital structure by creating LP Units (“the Reclassification”). Immediately after the Reclassification, 69.0 million LP Units were outstanding, of which 575,256 time vesting interests had not yet vested, and 2.4 million of performance vesting interests had not yet vested. In the first quarter of 2018, the Board of Directors vested the time-vesting units outstanding and we recognized the remaining $1.0 million of stock based compensation related to these LP units. Further in 2015, warrants to purchase 160,333 shares of Class A common stock were issued to holders of Class C interests, and options to purchase 4.4 million shares of Class A common stock were issued to holders of Class D interests as leverage restoration options. The exercise price of the warrants and the leverage restoration options is $18.00 per share. In connection with the Reclassification of the equity-based awards, we recognized $14.5 million modification charge in general and administrative expenses in the year ended January 2, 2016. In 2015, the Board of Directors approved the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the "Plan"). In August 2016, the Board of Directors determined that it was in the best interest of the Company to waive certain vesting criteria related to options to purchase 4.4 million shares of Class A common stock and certain performance-based LP Units. This waiver was accounted for as a modification of both interests. The fair value of the LP Units was based on the closing stock price of Summit Inc.’s shares of Class A common stock on the modification date and the fair value of the leverage restoration options was determined using the Black-Scholes, Merton model. The Company recognized $37.7 million in general and administrative expenses in the year ended December 31, 2016 related to the vesting of these performance-based awards. Omnibus Incentive Plan In 2015, our Board of Directors and stockholders adopted the Plan, which allows for grants of equity-based awards in the form of stock options, stock appreciation rights, restricted stock and restricted stock units, performance units, and other stock-based awards. The Plan authorizes the issuance of up to 13,500,000 shares of Class A common stock in the form of restricted stock units and stock options, of which 6.6 million shares were available for future grants as of December 29, 2018 . Restricted Stock Restricted Stock with Service-Based Vesting—Under the Plan, the Compensation Committee of the Board of Directors (“the Compensation Committee”) has granted restricted stock to members of the Board of Directors, executive officers and other key employees. These awards contain service conditions associated with continued employment or service. The terms of the restricted stock provide voting and regular dividend rights to holders of the awards. Upon vesting, the restrictions on the restricted stock lapse and the shares are considered issued and outstanding for accounting purposes. In each of 2018, 2017 and 2016, the Compensation Committee granted restricted stock to executives and key employees under the Plan as part of our annual equity award program, which vest over a three year period, subject to continued employment or service. From time to time, the Compensation Committee grants restricted stock to newly hired or promoted employees or other employees or consultants who have achieved extraordinary personal performance objectives. Further, in each of 2018, 2017 and 2016, the Compensation Committee granted 38,232 , 34,928 and 28,140 shares, respectively, to non-employee members of the Board of Directors for their annual service as directors. These restricted stock grants vest over a one year period. In measuring compensation expense associated with the grant of restricted stock, we use the fair value of the award, determined as the closing stock price for our common stock on the date of grant. Compensation expense is recorded monthly over the vesting period of the award. Restricted stock with Service- and Market-Condition-Based Vesting—In each of 2018, 2017 and 2016, the Compensation Committee granted restricted stock to certain members of our executive team as part of their annual compensation package. The restricted stock vests at the end of a three year performance period, based on our total stock return (“TSR”) ranking relative to companies in the S&P Building & Construction Select Industry Index, subject to continued employment. Compensation expense is recorded monthly over the vesting period of the awards. The following table summarizes information for the equity awards granted in 2018: Options Restricted Stock Units Performance Stock Units Warrants Weighted Weighted Weighted Weighted average grant- Number of average grant- Number of average grant- average grant- Number of date fair value restricted date fair value performance date fair value Number of date fair value options per unit stock units per unit stock units per unit warrants per unit Beginning balance—December 30, 2017 4,153,613 $ 9.13 508,586 $ 20.14 211,455 $ 23.69 102,778 $ 18.00 Granted — — 689,386 28.68 102,842 40.83 — — Forfeited (22,566 ) 10.91 (21,551 ) 28.11 (19,045 ) 26.26 — — Exercised (863,898 ) 8.88 — — — — (2,741 ) 18.00 Vested — — (252,113 ) 21.95 — — — — Balance—December 29, 2018 3,267,149 $ 9.09 924,308 $ 24.57 295,252 $ 29.12 100,037 $ 18.00 The fair value of the time-vesting options granted was estimated as of the grant date using the Black-Scholes-Merton model, which requires the input of subjective assumptions, including the expected volatility and the expected term. The fair value of the performance stock units granted was estimated as of the grant date using Monte Carlo simulations, which requires the input of subjective assumptions, including the expected volatility and the expected term. The following table presents the weighted average assumptions used to estimate the fair value of grants in 2018, 2017 and 2016: Options Performance Stock Units 2017 2016 2018 2017 2016 Risk-free interest rate 2.06% - 2.31% 1.75% - 1.97% 2.38% 1.45% 0.88% Dividend yield N/A N/A N/A N/A N/A Volatility 47% 48% 38% 39% 37% Expected term 7 years 10 years 3 years 3 years 3 years The risk-free rate is based on the yield at the date of grant of a U.S. Treasury security with a maturity period approximating the expected term. As Summit Holdings has not historically and does not plan to issue regular dividends, a dividend yield of zero was used. The volatility assumption is based on reported data of a peer group of publicly traded companies for which historical information was available adjusted for the Company’s capital structure. The expected term is based on expectations about future exercises and represents the period of time that the units granted are expected to be outstanding. Compensation expense for time-vesting interests granted is based on the grant date fair value. The Company recognizes compensation costs on a straight-line basis over the service period, which is generally the vesting period of the award. Forfeitures are recognized as they occur. Share-based compensation expense, which is recognized in general and administrative expenses, totaled $25.4 million , $49.9 million and $19.9 million in the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. As of December 29, 2018 , unrecognized compensation cost totaled $23.3 million . The weighted average remaining contractual term over which the unrecognized compensation cost is to be recognized is 1.8 years as of year-end 2018. As of December 29, 2018 , the intrinsic value of outstanding options, restricted stock units and performance stock units was zero, $11.4 million and $3.6 million , respectively, and the remaining contractual term was 6.2 years , 1.0 year and 1.1 years , respectively. The weighted average strike price of stock options outstanding as of December 29, 2018 was $18.54 per share. The intrinsic value of 1.9 million exercisable stock options as of December 29, 2018 was $11.5 million with a weighted average strike price of $18.26 and a weighted average remaining vesting period of 5.9 years .
Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-Based Compensation	Stock-Based Compensation Prior to the IPO and related Reorganization, the capital structure of Summit Holdings consisted of six different classes of limited partnership units, each of which was subject to unique distribution rights. In connection with the IPO and the related Reorganization, the limited partnership agreement of Summit Holdings was amended and restated to, among other things, modify its capital structure by creating LP Units (“the Reclassification”). Immediately after the Reclassification, 69.0 million LP Units were outstanding, of which 575,256 time vesting interests had not yet vested, and 2.4 million of performance vesting interests had not yet vested. In the first quarter of 2018, the Board of Directors vested the time-vesting units outstanding and we recognized the remaining $1.0 million of stock based compensation related to these LP units. Further in 2015, warrants to purchase 160,333 shares of Class A common stock were issued to holders of Class C interests, and options to purchase 4.4 million shares of Class A common stock were issued to holders of Class D interests as leverage restoration options. The exercise price of the warrants and the leverage restoration options is $18.00 per share. In connection with the Reclassification of the equity-based awards, we recognized $14.5 million modification charge in general and administrative expenses in the year ended January 2, 2016. In 2015, the Board of Directors approved the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the "Plan"). In August 2016, the Board of Directors determined that it was in the best interest of the Company to waive certain vesting criteria related to options to purchase 4.4 million shares of Class A common stock and certain performance-based LP Units. This waiver was accounted for as a modification of both interests. The fair value of the LP Units was based on the closing stock price of Summit Inc.’s shares of Class A common stock on the modification date and the fair value of the leverage restoration options was determined using the Black-Scholes, Merton model. The Company recognized $37.7 million in general and administrative expenses in the year ended December 31, 2016 related to the vesting of these performance-based awards. Omnibus Incentive Plan In 2015, our Board of Directors and stockholders adopted the Plan, which allows for grants of equity-based awards in the form of stock options, stock appreciation rights, restricted stock and restricted stock units, performance units, and other stock-based awards. The Plan authorizes the issuance of up to 13,500,000 shares of Class A common stock in the form of restricted stock units and stock options, of which 6.6 million shares were available for future grants as of December 29, 2018 . Restricted Stock Restricted Stock with Service-Based Vesting —Under the Plan, the Compensation Committee of the Board of Directors (“the Compensation Committee”) has granted restricted stock to members of the Board of Directors, executive officers and other key employees. These awards contain service conditions associated with continued employment or service. The terms of the restricted stock provide voting and regular dividend rights to holders of the awards. Upon vesting, the restrictions on the restricted stock lapse and the shares are considered issued and outstanding for accounting purposes. In each of 2018, 2017 and 2016, the Compensation Committee granted restricted stock to executives and key employees under the Plan as part of our annual equity award program, which vest over a three year period, subject to continued employment or service. From time to time, the Compensation Committee grants restricted stock to newly hired or promoted employees or other employees or consultants who have achieved extraordinary personal performance objectives. Further, in each of 2018, 2017 and 2016, the Compensation Committee granted 38,232 , 34,928 and 28,140 shares, respectively, to non-employee members of the Board of Directors for their annual service as directors. These restricted stock grants vest over a one year period. In measuring compensation expense associated with the grant of restricted stock, we use the fair value of the award, determined as the closing stock price for our common stock on the date of grant. Compensation expense is recorded monthly over the vesting period of the award. Restricted stock with Service- and Market-Condition-Based Vesting —In each of 2018, 2017 and 2016, the Compensation Committee granted restricted stock to certain members of our executive team as part of their annual compensation package. The restricted stock vests at the end of a three years performance period, based on our total stock return (“TSR”) ranking relative to companies in the S&P Building & Construction Select Industry Index, subject to continued employment. Compensation expense is recorded monthly over the vesting period of the awards. The following table summarizes information for the equity awards granted in 2018: Options Restricted Stock Units Performance Stock Units Warrants Weighted Weighted Weighted Weighted average grant- Number of average grant- Number of average grant- average grant- Number of date fair value restricted date fair value performance date fair value Number of date fair value options per unit stock units per unit stock units per unit warrants per unit Beginning balance—December 30, 2017 4,153,613 $ 9.13 508,586 $ 20.14 211,455 $ 23.69 102,778 $ 18.00 Granted — — 689,386 28.68 102,842 40.83 — — Forfeited (22,566 ) 10.91 (21,551 ) 28.11 (19,045 ) 26.26 — — Exercised (863,898 ) 8.88 — — — — (2,741 ) 18.00 Vested — — (252,113 ) 21.95 — — — — Balance—December 29, 2018 3,267,149 $ 9.09 924,308 $ 24.57 295,252 $ 29.12 100,037 $ 18.00 The fair value of the time-vesting options granted was estimated as of the grant date using the Black-Scholes-Merton model, which requires the input of subjective assumptions, including the expected volatility and the expected term. The fair value of the performance stock units granted was estimated as of the grant date using Monte Carlo simulations, which requires the input of subjective assumptions, including the expected volatility and the expected term. The following table presents the weighted average assumptions used to estimate the fair value of grants in 2018, 2017 and 2016: Options Performance Stock Units 2017 2016 2018 2017 2016 Risk-free interest rate 2.06% - 2.31% 1.75% - 1.97% 2.38% 1.45% 0.88% Dividend yield N/A N/A N/A N/A N/A Volatility 47% 48% 38% 39% 37% Expected term 7 years 10 years 3 years 3 years 3 years The risk-free rate is based on the yield at the date of grant of a U.S. Treasury security with a maturity period approximating the expected term. As Summit Holdings has not historically and does not plan to issue regular dividends, a dividend yield of zero was used. The volatility assumption is based on reported data of a peer group of publicly traded companies for which historical information was available adjusted for the Company’s capital structure. The expected term is based on expectations about future exercises and represents the period of time that the units granted are expected to be outstanding. Compensation expense for time-vesting interests granted is based on the grant date fair value. The Company recognizes compensation costs on a straight-line basis over the service period, which is generally the vesting period of the award. Forfeitures are recognized as they occur. Share-based compensation expense, which is recognized in general and administrative expenses, totaled $25.4 million , $49.9 million and $19.9 million in the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. As of December 29, 2018 , unrecognized compensation cost totaled $23.3 million . The weighted average remaining contractual term over which the unrecognized compensation cost is to be recognized is 1.8 years as of year-end 2018. As of December 29, 2018 , the intrinsic value of outstanding options, restricted stock units and performance stock units was zero , $11.4 million and $3.6 million , respectively, and the remaining contractual term was 6.2 years , 1.0 years and 1.1 years , respectively. The weighted average strike price of stock options outstanding as of December 29, 2018 was $18.54 per share. The intrinsic value of 1.9 million exercisable stock options as of December 29, 2018 was $11.5 million with a weighted average strike price of $18.26 and a weighted average remaining vesting period of 5.9 years .

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Employee Benefit Plans	Employee Benefit Plans Defined Contribution Plan —The Company sponsors employee 401(k) savings plans for its employees, including certain union employees. The plans provide for various required and discretionary Company matches of employees’ eligible compensation contributed to the plans. The expense for the defined contribution plans was $11.2 million , $9.3 million and $8.6 million for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. Defined Benefit and Other Postretirement Benefits Plans —The Company’s subsidiary, Continental Cement, sponsors two noncontributory defined benefit pension plans for hourly and salaried employees. The plans are closed to new participants and benefits are frozen. As a result of the collective bargaining unit negotiations in 2017, the hourly defined benefit pension plan was amended to stop future benefit accruals for the Davenport employees effective December 31, 2017. Pension benefits for eligible hourly employees are based on a monthly pension factor for each year of credited service. Pension benefits for eligible salaried employees are generally based on years of service and average eligible compensation. Continental Cement also sponsors two unfunded healthcare and life insurance benefits plans for certain eligible retired employees. Effective January 1, 2014, the plan covering employees of the Hannibal, Missouri location was amended to eliminate all future retiree health and life coverage for current employees. During 2015, Continental Cement adopted one new unfunded healthcare plan to provide benefits prior to Medicare eligibility for certain hourly employees of the Davenport, Iowa location. The funded status of the pension and other postretirement benefit plans is recognized in the consolidated balance sheets as the difference between the fair value of plan assets and the benefit obligations. For defined benefit pension plans, the benefit obligation is the projected benefit obligation (“PBO”) and for the healthcare and life insurance benefits plans, the benefit obligation is the accumulated postretirement benefit obligation (“APBO”). The PBO represents the actuarial present value of benefits expected to be paid upon retirement based on estimated future compensation levels. However, since the plans’ participants are not subject to future compensation increases, the plans’ PBO equals the accumulated benefit obligation (“ABO”). The APBO represents the actuarial present value of postretirement benefits attributed to employee services already rendered. The fair value of plan assets represents the current market value of assets held by an irrevocable trust fund for the sole benefit of participants. The measurement of the benefit obligations is based on the Company’s estimates and actuarial valuations. These valuations reflect the terms of the plan and use participant-specific information, such as compensation, age and years of service, as well as certain assumptions that require significant judgment, including estimates of discount rates, expected return on plan assets, rate of compensation increases, interest-crediting rates and mortality rates. The Company uses December 31 as the measurement date for its defined benefit pension and other postretirement benefit plans. Obligations and Funded Status —The following information is as of December 29, 2018 and December 30, 2017 and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. Change in benefit obligations: Beginning of period $ 27,984 $ 9,793 $ 27,608 $ 12,770 Service cost 67 170 285 184 Interest cost 898 317 998 365 Actuarial (gain) loss (3,136 ) (173 ) 1,182 (338 ) Curtailments — — (430 ) — Change in plan provision — — — (2,325 ) Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 24,203 $ 9,203 $ 27,984 $ 9,793 Change in fair value of plan assets: Beginning of period $ 19,012 $ — $ 18,395 $ — Actual return on plan assets (551 ) — 1,415 — Employer contributions 598 904 861 863 Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 17,449 $ — $ 19,012 $ — Funded status of plans $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Current liabilities $ — $ — $ — $ (702 ) Noncurrent liabilities (6,754 ) (9,203 ) (8,972 ) (9,091 ) Liability recognized $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Amounts recognized in accumulated other comprehensive income: Net actuarial (gain) loss $ (1,300 ) $ 1,995 $ 9,341 $ 2,285 Prior service cost (312 ) (2,172 ) — (2,413 ) Total amount recognized $ (1,612 ) $ (177 ) $ 9,341 $ (128 ) The amount recognized in accumulated other comprehensive income (“AOCI”) is the actuarial loss (credit) and prior service cost, which has not yet been recognized in periodic benefit cost. 2018 2017 2016 Pension Healthcare Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. benefits & Life Ins. Amounts recognized in other comprehensive (income) loss: Net actuarial (loss) gain $ (1,300 ) $ (172 ) $ 1,068 $ (338 ) $ 688 $ (682 ) Prior service cost — — — (572 ) — 64 Amortization of prior year service cost — 241 — 168 — 174 Curtailment benefit — — (429 ) — — — Amortization of gain (312 ) (118 ) (547 ) (64 ) (463 ) (207 ) Adjustment to plan benefits — — — (414 ) — — Total amount recognized $ (1,612 ) $ (49 ) $ 92 $ (1,220 ) $ 225 $ (651 ) Components of net periodic benefit cost: Service cost $ 67 $ 170 $ 285 $ 184 $ 279 $ 230 Interest cost 898 317 998 365 1,049 470 Amortization of gain 312 118 547 64 463 207 Expected return on plan assets (1,284 ) — (1,302 ) — (1,386 ) — Curtailments — — — — — — Amortization of prior service credit — (241 ) — (168 ) — (174 ) Net periodic (expense) benefit cost $ (7 ) $ 364 $ 528 $ 445 $ 405 $ 733 Assumptions— Weighted-average assumptions used to determine the benefit obligations as of year-end 2018 and 2017 are: 2018 2017 Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.90% - 4.02% 3.87% - 3.91% 3.23% - 3.37% 3.20% - 3.25% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A Weighted-average assumptions used to determine net periodic benefit cost for years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Healthcare Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.23% - 3.37% 3.20% - 3.25% 3.61% - 3.81% 3.54% - 3.65% 3.74% - 3.97% 3.34% - 3.80% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A 7.30% N/A The expected long-term return on plan assets is based upon the Plans’ consideration of historical and forward-looking returns and the Company’s estimation of what a portfolio, with the target allocation described below, will earn over a long-term horizon. The discount rate is derived using the Citigroup Pension Discount Curve. Assumed health care cost trend rates were 8.0% grading to 4.5% as of year-end 2018 and 2017 . Assumed health care cost trend rates have a significant effect on the amounts reported for the Company’s healthcare and life insurance benefits plans. A one percentage-point change in assumed health care cost trend rates would have the following effects as of year-end 2018 and 2017 : 2018 2017 Increase Decrease Increase Decrease Total service cost and interest cost components $ 31 $ (27 ) $ 39 $ (33 ) APBO 765 (690 ) 857 (769 ) Plan Assets —The defined benefit pension plans’ (the “Plans”) investment strategy is to minimize investment risk while generating acceptable returns. The Plans currently invest a relatively high proportion of the plan assets in fixed income securities, while the remainder is invested in equity securities, cash reserves and precious metals. The equity securities are diversified into funds with growth and value investment strategies. The target allocation for plan assets is as follows: equity securities— 30% ; fixed income securities— 63% ; cash reserves— 5% ; and precious metals— 2% . The Plans’ current investment allocations are within the tolerance of the target allocation. The Company had no Level 3 investments as of or for the years ended December 29, 2018 and December 30, 2017 . At year-end 2018 and 2017 , the Plans’ assets were invested predominantly in fixed-income securities and publicly traded equities, but may invest in other asset classes in the future subject to the parameters of the investment policy. The Plans’ investments in fixed-income assets include U.S. Treasury and U.S. agency securities and corporate bonds. The Plans’ investments in equity assets include U.S. and international securities and equity funds. The Company estimates the fair value of the Plans’ assets using various valuation techniques and, to the extent available, quoted market prices in active markets or observable market inputs. The descriptions and fair value methodologies for the Plans’ assets are as follows: Fixed Income Securities —Corporate and government bonds are classified as Level 2 assets, as they are either valued at quoted market prices from observable pricing sources at the reporting date or valued based upon comparable securities with similar yields and credit ratings. Equity Securities —Equity securities are valued at the closing market price reported on a U.S. exchange where the security is actively traded and are therefore classified as Level 1 assets. Cash —The carrying amounts of cash approximate fair value due to the short-term maturity. Precious Metals— Precious metals are valued at the closing market price reported on a U.S. exchange where the security is actively traded and are therefore classified as Level 1 assets. The fair value of the Plans’ assets by asset class and fair value hierarchy level as of December 29, 2018 and December 30, 2017 are as follows: 2018 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,547 $ 3,547 $ — Intermediate—corporate 3,437 — 3,437 Short-term—government 756 756 — Short-term—corporate 957 — 957 International 1,143 — 1,143 Equity securities: U.S. Large cap value 978 978 — U.S. Large cap growth 976 976 — U.S. Mid cap value 471 471 — U.S. Mid cap growth 496 496 — U.S. Small cap value 463 463 — U.S. Small cap growth 474 474 — Managed Futures 355 — 355 International 1,004 329 675 Emerging Markets 362 362 — Commodities Broad Basket 1,048 388 660 Cash 982 982 — Total $ 17,449 $ 10,222 $ 7,227 2017 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,620 $ 3,068 $ 552 Intermediate—corporate 3,872 — 3,872 Short-term—government 497 497 — Short-term—corporate 1,702 — 1,702 Equity securities: U.S. Large cap value 1,765 1,765 — U.S. Large cap growth 588 588 — U.S. Mid cap value 586 586 — U.S. Mid cap growth 586 586 — U.S. Small cap value 571 571 — U.S. Small cap growth 580 580 — Managed Futures 392 — 392 International 1,547 677 870 Commodities Broad Basket 801 — 801 Cash 1,522 — 1,522 Precious metals 383 383 — Total $ 19,012 $ 9,301 $ 9,711 Cash Flows —The Company expects to contribute approximately $1.0 million in 2019 to both its pension plans and to its healthcare and life insurance benefits plans. The estimated benefit payments for each of the next five years and the five-year period thereafter are as follows: Pension Healthcare and Life benefits Insurance Benefits 2019 $ 1,736 $ 687 2020 1,712 697 2021 1,680 681 2022 1,678 669 2023 1,676 664 2024 - 2028 7,806 3,415 Multiemployer Pension Plans — In 2018, The Company acquired Buildex, LLC and assumed its obligation to contribute to a number of multiemployer defined benefit pension plans under the terms of collective-bargaining agreements that cover its union-represented employees. The risks of participating in multiemployer pension plans are different from single-employer plans. Assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. If a participating employer ceases contributing to the plan, the unfunded obligations of the plan are the responsibility of the remaining participating employers. The Company's participation in these plans for the annual period ended December 31, 2018, is outlined in the table below. The ''EIN/Pension Plan Number" column provides the Employer Identification Number (EIN) and the three-digit plan number, if applicable. Unless otherwise noted, the most recent Pension Protection Act (PPA) zone status available in 2018 and 2017 is for the plan 's year end at December 31, 2017, and December 31, 2016, respectively. The zone status is based on information the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the red zone are generally less than 65% funded, plans in the yellow zone are less than 80% funded and plans in the green zone are at least 80% funded. The "FIP/RP Status Pending/Implemented" column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. The "Surcharge Imposed" column indicates whether a surcharge has been imposed on contributions to the plan. The last column lists the expiration date(s) of the collective-bargaining agreement(s) to which the plans are subject. There have been no significant changes that affect the comparability of 2018 and 2017 contributions. Expiration Date of Pension Protection Act FIP/RP Status Contributions of Company Collective- Pension EIN/ Pension Zone Status Pending/ ($ in thousands) Surcharge Bargaining Trust Fund Plan Number 2018 2017 Implemented 2018 2017 Imposed Agreement (1) Construction Industry Laborers Pension Fund 43-6060737/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None $ 115 $ 104 No 12/31/2018 Operating Engineers Local 101 Pension Plan 43-6059213/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None 26 30 No 12/31/2018 Total Contributions $ 141 $ 134 _____________________ (1) C urrently in final negotiations to extend both collective-bargaining agreements. The Company was not listed as providing more than 5% of the total contributions for the Operating Engineers Local 101 Pension Plan for the plan years 2017 and 2016 per the plan's Form 5500. The Company did not provide over 5% of total contributions in 2017 or 2016 for the Construction Industry Laborers Pension Fund per the plan's Form 5500. As of the date of the filing of this annual report on Form 10-K, Forms 5500 were not available for the plan year ending December 31, 2018.
Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Employee Benefit Plans	Employee Benefit Plans Defined Contribution Plan —The Company sponsors employee 401(k) savings plans for its employees, including certain union employees. The plans provide for various required and discretionary Company matches of employees’ eligible compensation contributed to the plans. The expense for the defined contribution plans was $11.2 million , $9.3 million and $8.6 million for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , respectively. Defined Benefit and Other Postretirement Benefits Plans —The Company’s subsidiary, Continental Cement, sponsors two noncontributory defined benefit pension plans for hourly and salaried employees. The plans are closed to new participants and benefits are frozen. As a result of the collective bargaining unit negotiations in 2017, the hourly defined benefit pension plan was amended to stop future benefit accruals for the Davenport employees effective December 31, 2017. Pension benefits for eligible hourly employees are based on a monthly pension factor for each year of credited service. Pension benefits for eligible salaried employees are generally based on years of service and average eligible compensation. Continental Cement also sponsors two unfunded healthcare and life insurance benefits plans for certain eligible retired employees. Effective January 1, 2014, the plan covering employees of the Hannibal, Missouri location was amended to eliminate all future retiree health and life coverage for current employees. During 2015, Continental Cement adopted one new unfunded healthcare plan to provide benefits prior to Medicare eligibility for certain hourly employees of the Davenport, Iowa location. The funded status of the pension and other postretirement benefit plans is recognized in the consolidated balance sheets as the difference between the fair value of plan assets and the benefit obligations. For defined benefit pension plans, the benefit obligation is the projected benefit obligation (“PBO”) and for the healthcare and life insurance benefits plans, the benefit obligation is the accumulated postretirement benefit obligation (“APBO”). The PBO represents the actuarial present value of benefits expected to be paid upon retirement based on estimated future compensation levels. However, since the plans’ participants are not subject to future compensation increases, the plans’ PBO equals the accumulated benefit obligation (“ABO”). The APBO represents the actuarial present value of postretirement benefits attributed to employee services already rendered. The fair value of plan assets represents the current market value of assets held by an irrevocable trust fund for the sole benefit of participants. The measurement of the benefit obligations is based on the Company’s estimates and actuarial valuations. These valuations reflect the terms of the plan and use participant-specific information, such as compensation, age and years of service, as well as certain assumptions that require significant judgment, including estimates of discount rates, expected return on plan assets, rate of compensation increases, interest-crediting rates and mortality rates. The Company uses December 31 as the measurement date for its defined benefit pension and other postretirement benefit plans. Obligations and Funded Status —The following information is as of December 29, 2018 and December 30, 2017 and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. Change in benefit obligations: Beginning of period $ 27,984 $ 9,793 $ 27,608 $ 12,770 Service cost 67 170 285 184 Interest cost 898 317 998 365 Actuarial (gain) loss (3,136 ) (173 ) 1,182 (338 ) Curtailments — — (430 ) — Change in plan provision — — — (2,325 ) Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 24,203 $ 9,203 $ 27,984 $ 9,793 Change in fair value of plan assets: Beginning of period $ 19,012 $ — $ 18,395 $ — Actual return on plan assets (551 ) — 1,415 — Employer contributions 598 904 861 863 Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 17,449 $ — $ 19,012 $ — Funded status of plans $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Current liabilities $ — $ — $ — $ (702 ) Noncurrent liabilities (6,754 ) (9,203 ) (8,972 ) (9,091 ) Liability recognized $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Amounts recognized in accumulated other comprehensive income: Net actuarial (gain) loss $ (1,300 ) $ 1,995 $ 9,341 $ 2,285 Prior service cost (312 ) (2,172 ) — (2,413 ) Total amount recognized $ (1,612 ) $ (177 ) $ 9,341 $ (128 ) The amount recognized in accumulated other comprehensive income (“AOCI”) is the actuarial loss (credit) and prior service cost, which has not yet been recognized in periodic benefit cost. 2018 2017 2016 Pension Healthcare Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. benefits & Life Ins. Amounts recognized in other comprehensive (income) loss: Net actuarial (loss) gain $ (1,300 ) $ (172 ) $ 1,068 $ (338 ) $ 688 $ (682 ) Prior service cost — — — (572 ) — 64 Amortization of prior year service cost — 241 — 168 — 174 Curtailment benefit — — (429 ) — — — Amortization of gain (312 ) (118 ) (547 ) (64 ) (463 ) (207 ) Adjustment to plan benefits — — — (414 ) — — Total amount recognized $ (1,612 ) $ (49 ) $ 92 $ (1,220 ) $ 225 $ (651 ) Components of net periodic benefit cost: Service cost $ 67 $ 170 $ 285 $ 184 $ 279 $ 230 Interest cost 898 317 998 365 1,049 470 Amortization of gain 312 118 547 64 463 207 Expected return on plan assets (1,284 ) — (1,302 ) — (1,386 ) — Curtailments — — — — — — Amortization of prior service credit — (241 ) — (168 ) — (174 ) Net periodic (expense) benefit cost $ (7 ) $ 364 $ 528 $ 445 $ 405 $ 733 Assumptions— Weighted-average assumptions used to determine the benefit obligations as of year-end 2018 and 2017 are: 2018 2017 Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.90% - 4.02% 3.87% - 3.91% 3.23% - 3.37% 3.20% - 3.25% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A Weighted-average assumptions used to determine net periodic benefit cost for years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Healthcare Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.23% - 3.37% 3.20% - 3.25% 3.61% - 3.81% 3.54% - 3.65% 3.74% - 3.97% 3.34% - 3.80% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A 7.30% N/A The expected long-term return on plan assets is based upon the Plans’ consideration of historical and forward-looking returns and the Company’s estimation of what a portfolio, with the target allocation described below, will earn over a long-term horizon. The discount rate is derived using the Citigroup Pension Discount Curve. Assumed health care cost trend rates were 8.0% grading to 4.5% as of year-end 2018 and 2017 . Assumed health care cost trend rates have a significant effect on the amounts reported for the Company’s healthcare and life insurance benefits plans. A one percentage-point change in assumed health care cost trend rates would have the following effects as of year-end 2018 and 2017 : 2018 2017 Increase Decrease Increase Decrease Total service cost and interest cost components $ 31 $ (27 ) $ 39 $ (33 ) APBO 765 (690 ) 857 (769 ) Plan Assets —The defined benefit pension plans’ (the “Plans”) investment strategy is to minimize investment risk while generating acceptable returns. The Plans currently invest a relatively high proportion of the plan assets in fixed income securities, while the remainder is invested in equity securities, cash reserves and precious metals. The equity securities are diversified into funds with growth and value investment strategies. The target allocation for plan assets is as follows: equity securities— 30% ; fixed income securities— 63% ; cash reserves— 5% ; and precious metals— 2% . The Plans’ current investment allocations are within the tolerance of the target allocation. The Company had no Level 3 investments as of or for the years ended December 29, 2018 and December 30, 2017 . At year-end 2018 and 2017 , the Plans’ assets were invested predominantly in fixed-income securities and publicly traded equities, but may invest in other asset classes in the future subject to the parameters of the investment policy. The Plans’ investments in fixed-income assets include U.S. Treasury and U.S. agency securities and corporate bonds. The Plans’ investments in equity assets include U.S. and international securities and equity funds. The Company estimates the fair value of the Plans’ assets using various valuation techniques and, to the extent available, quoted market prices in active markets or observable market inputs. The descriptions and fair value methodologies for the Plans’ assets are as follows: Fixed Income Securities —Corporate and government bonds are classified as Level 2 assets, as they are either valued at quoted market prices from observable pricing sources at the reporting date or valued based upon comparable securities with similar yields and credit ratings. Equity Securities —Equity securities are valued at the closing market price reported on a U.S. exchange where the security is actively traded and are therefore classified as Level 1 assets. Cash —The carrying amounts of cash approximate fair value due to the short-term maturity. Precious Metals— Precious metals are valued at the closing market price reported on a U.S. exchange where the security is actively traded and are therefore classified as Level 1 assets. The fair value of the Plans’ assets by asset class and fair value hierarchy level as of December 29, 2018 and December 30, 2017 are as follows: 2018 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,547 $ 3,547 $ — Intermediate—corporate 3,437 — 3,437 Short-term—government 756 756 — Short-term—corporate 957 — 957 International 1,143 — 1,143 Equity securities: U.S. Large cap value 978 978 — U.S. Large cap growth 976 976 — U.S. Mid cap value 471 471 — U.S. Mid cap growth 496 496 — U.S. Small cap value 463 463 — U.S. Small cap growth 474 474 — Managed Futures 355 — 355 International 1,004 329 675 Emerging Markets 362 362 — Commodities Broad Basket 1,048 388 660 Cash 982 982 — Total $ 17,449 $ 10,222 $ 7,227 2017 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,620 $ 3,068 $ 552 Intermediate—corporate 3,872 — 3,872 Short-term—government 497 497 — Short-term—corporate 1,702 — 1,702 Equity securities: U.S. Large cap value 1,765 1,765 — U.S. Large cap growth 588 588 — U.S. Mid cap value 586 586 — U.S. Mid cap growth 586 586 — U.S. Small cap value 571 571 — U.S. Small cap growth 580 580 — Managed Futures 392 — 392 International 1,547 677 870 Commodities Broad Basket 801 — 801 Cash 1,522 — 1,522 Precious metals 383 383 — Total $ 19,012 $ 9,301 $ 9,711 Cash Flows —The Company expects to contribute approximately $1.0 million in 2019 to both its pension plans and to its healthcare and life insurance benefits plans. The estimated benefit payments for each of the next five years and the five-year period thereafter are as follows: Pension Healthcare and Life benefits Insurance Benefits 2019 $ 1,736 $ 687 2020 1,712 697 2021 1,680 681 2022 1,678 669 2023 1,676 664 2024 - 2028 7,806 3,415 Multiemployer Pension Plans — In 2018, The Company acquired Buildex, LLC and assumed its obligation to contribute to a number of multiemployer defined benefit pension plans under the terms of collective-bargaining agreements that cover its union-represented employees. The risks of participating in multiemployer pension plans are different from single-employer plans. Assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. If a participating employer ceases contributing to the plan, the unfunded obligations of the plan are the responsibility of the remaining participating employers. The Company's participation in these plans for the annual period ended December 31, 2018, is outlined in the table below. The ''EIN/Pension Plan Number" column provides the Employer Identification Number (EIN) and the three-digit plan number, if applicable. Unless otherwise noted, the most recent Pension Protection Act (PPA) zone status available in 2018 and 2017 is for the plan 's year end at December 31, 2017, and December 31, 2016, respectively. The zone status is based on information the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the red zone are generally less than 65% funded, plans in the yellow zone are less than 80% funded and plans in the green zone are at least 80% funded. The "FIP/RP Status Pending/Implemented" column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. The "Surcharge Imposed" column indicates whether a surcharge has been imposed on contributions to the plan. The last column lists the expiration date(s) of the collective-bargaining agreement(s) to which the plans are subject. There have been no significant changes that affect the comparability of 2018 and 2017 contributions. Expiration Date of Pension Protection Act FIP/RP Status Contributions of Company Collective- Pension EIN/ Pension Zone Status Pending/ ($ in thousands) Surcharge Bargaining Trust Fund Plan Number 2018 2017 Implemented 2018 2017 Imposed Agreement (1) Construction Industry Laborers Pension Fund 43-6060737/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None $ 115 $ 104 No 12/31/2018 Operating Engineers Local 101 Pension Plan 43-6059213/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None 26 30 No 12/31/2018 Total Contributions $ 141 $ 134 ______________________ (1) Currently in final negotiations to extend both collective-bargaining agreements. The Company was not listed as providing more than 5% of the total contributions for the Operating Engineers Local 101 Pension Plan for the plan years 2017 and 2016 per the plan's Form 5500. The Company did not provide over 5% of total contributions in 2017 or 2016 for the Construction Industry Laborers Pension Fund per the plan's Form 5500. As of the date of the filing of this annual report on Form 10-K, Forms 5500 were not available for the plan year ending December 31, 2018.

Accrued Mining and Landfill Rec

Accrued Mining and Landfill Reclamation	12 Months Ended
	Dec. 29, 2018
Asset Retirement Obligations [Line Items]
Accrued Mining and Landfill Reclamation	Accrued Mining and Landfill Reclamation The Company has asset retirement obligations arising from regulatory or contractual requirements to perform certain reclamation activities at the time that certain quarries and landfills are closed, which are primarily included in other noncurrent liabilities on the consolidated balance sheets. The current portion of the liabilities, $4.1 million and $3.9 million as of December 29, 2018 and December 30, 2017 , respectively, is included in accrued expenses on the consolidated balance sheets. The total undiscounted anticipated costs for site reclamation as of December 29, 2018 and December 30, 2017 were $92.5 million and $67.9 million , respectively. The liabilities were initially measured at fair value and are subsequently adjusted for accretion expense, payments and changes in the amount or timing of the estimated cash flows. The corresponding asset retirement costs are capitalized as part of the carrying amount of the related long-lived asset and depreciated over the asset’s remaining useful life. The following table presents the activity for the asset retirement obligations for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 Beginning balance $ 24,329 $ 23,906 Acquired obligations 3,937 2,303 Change in cost estimate 2,808 (1,759 ) Settlement of reclamation obligations (1,680 ) (1,996 ) Accretion expense 1,605 1,875 Ending balance $ 30,999 $ 24,329
Summit Materials, LLC
Asset Retirement Obligations [Line Items]
Accrued Mining and Landfill Reclamation	Accrued Mining and Landfill Reclamation The Company has asset retirement obligations arising from regulatory or contractual requirements to perform certain reclamation activities at the time that certain quarries and landfills are closed, which are primarily included in other noncurrent liabilities on the consolidated balance sheets. The current portion of the liabilities, $4.1 million and $3.9 million as of December 29, 2018 and December 30, 2017 , respectively, is included in accrued expenses on the consolidated balance sheets. The total undiscounted anticipated costs for site reclamation as of December 29, 2018 and December 30, 2017 were $92.5 million and $67.9 million , respectively. The liabilities were initially measured at fair value and are subsequently adjusted for accretion expense, payments and changes in the amount or timing of the estimated cash flows. The corresponding asset retirement costs are capitalized as part of the carrying amount of the related long-lived asset and depreciated over the asset’s remaining useful life. The following table presents the activity for the asset retirement obligations for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 Beginning balance $ 24,329 $ 23,906 Acquired obligations 3,937 2,303 Change in cost estimate 2,808 (1,759 ) Settlement of reclamation obligations (1,680 ) (1,996 ) Accretion expense 1,605 1,875 Ending balance $ 30,999 $ 24,329

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 29, 2018
Loss Contingencies [Line Items]
Commitments and Contingencies	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 current pending or threatened claims and litigation will not have a material effect on the Company’s consolidated financial position, results of operations or liquidity. The Company records legal fees as incurred. In March 2018, we were notified of an investigation by the Canadian Competition Bureau (the “CCB”) into pricing practices by certain asphalt paving contractors in British Columbia, including Winvan Paving, Ltd. (“Winvan”). We believe the investigation is focused on time periods prior to our April 2017 acquisition of Winvan and we are cooperating with the CCB. Although we currently do not believe this matter will have a material adverse effect on our business, financial condition or results of operations, we are not able to predict the ultimate outcome or cost of the investigation at this time. Environmental Remediation and Site Restoration— 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 condition, results of operations or liquidity. Other— The Company is obligated under various firm purchase commitments for certain raw materials and services that are in the ordinary course of business. 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 condition, results of operations and cash flows of the Company. The terms of the purchase commitments generally approximate one year .
Summit Materials, LLC
Loss Contingencies [Line Items]
Commitments and Contingencies	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 current pending or threatened claims and litigation will not have a material effect on the Company’s consolidated financial position, results of operations or liquidity. The Company records legal fees as incurred. In March 2018, we were notified of an investigation by the Canadian Competition Bureau (the “CCB”) into pricing practices by certain asphalt paving contractors in British Columbia, including Winvan Paving, Ltd. (“Winvan”). We believe the investigation is focused on time periods prior to our April 2017 acquisition of Winvan and we are cooperating with the CCB. Although we currently do not believe this matter will have a material adverse effect on our business, financial condition or results of operations, we are not able to predict the ultimate outcome or cost of the investigation at this time. Environmental Remediation and Site Restoration— 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 condition, results of operations or liquidity. Other— The Company is obligated under various firm purchase commitments for certain raw materials and services that are in the ordinary course of business. 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 condition, results of operations and cash flows of the Company. The terms of the purchase commitments generally approximate one year .

Leasing Arrangements

Leasing Arrangements	12 Months Ended
	Dec. 29, 2018
Lease Rental Expenses [Line Items]
Leasing Arrangements	Leasing Arrangements Rent expense, which primarily relates to land, plants and equipment, during the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was $25.2 million , $21.7 million and $18.6 million , respectively. The Company has lease agreements associated with quarry facilities under which royalty payments are made. The payments are generally based on tons sold in a particular period; however, certain agreements have minimum annual payments. Royalty expense recorded in cost of revenue during the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was $20.1 million , $18.7 million and $15.6 million , respectively. Minimum contractual commitments for the subsequent five years under long-term operating leases and under royalty agreements are as follows: Operating Royalty Leases Agreements 2019 $ 9,479 $ 7,124 2020 8,101 6,929 2021 6,701 6,665 2022 4,279 6,742 2023 3,411 6,656
Summit Materials, LLC
Lease Rental Expenses [Line Items]
Leasing Arrangements	Leasing Arrangements Rent expense, which primarily relates to land, plants and equipment, during the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was $25.2 million , $21.7 million and $18.6 million , respectively. The Company has lease agreements associated with quarry facilities under which royalty payments are made. The payments are generally based on tons sold in a particular period; however, certain agreements have minimum annual payments. Royalty expense recorded in cost of revenue during the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was $20.1 million , $18.7 million and $15.6 million , respectively. Minimum contractual commitments for the subsequent five years under long-term operating leases and under royalty agreements are as follows: Operating Royalty Leases Agreements 2019 $ 9,479 $ 7,124 2020 8,101 6,929 2021 6,701 6,665 2022 4,279 6,742 2023 3,411 6,656

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 29, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Financial Instruments	Fair Value of Financial Instruments 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. The Company has entered into interest rate derivatives on $200.0 million of its term loan borrowings to add stability to interest expense and to manage its exposure to interest rate movements. The interest rate derivative expires in September 2019. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income and will be subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The fair value of contingent consideration and derivatives as of December 29, 2018 and December 30, 2017 was: 2018 2017 Current portion of acquisition-related liabilities and Accrued expenses: Contingent consideration $ 1,394 $ 594 Cash flow hedges — 488 Acquisition-related liabilities and Other noncurrent liabilities Contingent consideration $ 5,175 $ 34,301 Cash flow hedges — 492 The fair value accounting guidance establishes the following fair value hierarchy that prioritizes the inputs used to measure fair value: Level 1 — Unadjusted quoted prices for identical assets or liabilities in active markets. Level 2 — Inputs other than Level 1 that are based on observable market data, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in inactive markets, inputs that are observable that are not prices and inputs that are derived from or corroborated by observable markets. Level 3 — Valuations developed from unobservable data, reflecting the Company’s own assumptions, which market participants would use in pricing the asset or liability. The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 10.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the cash flow hedges are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material adjustments to the fair value of contingent consideration in 2018 or 2017 , or to cash flow hedges in 2018 or 2017 . 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 December 29, 2018 and December 30, 2017 were: December 29, 2018 December 30, 2017 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt(1) $ 1,777,722 $ 1,828,159 $ 1,893,239 $ 1,832,455 Level 3 Current portion of deferred consideration and noncompete obligations(2) 32,876 32,876 13,493 13,493 Long term portion of deferred consideration and noncompete obligations(3) 44,293 44,293 23,834 23,834 _____________________ (1) $6.4 million and $4.8 million included in current portion of debt as of December 29, 2018 and December 30, 2017 , respectively. (2) Included in current portion of acquisition-related liabilities on the consolidated balance sheets. (3) Included in acquisition-related liabilities on the consolidated balance sheets. The fair value of debt was determined based on observable, or Level 2 inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk. The discount rate used is generally consistent with that used when the obligations were initially recorded. Securities with a maturity of three months or less are considered cash equivalents and the fair value of these assets approximates their carrying value.
Summit Materials, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Financial Instruments	Fair Value of Financial Instruments 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. The Company has entered into interest rate derivatives on $200.0 million of its term loan borrowings to add stability to interest expense and to manage its exposure to interest rate movements. The interest rate derivative expires in September 2019. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income and will be subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The fair value of contingent consideration and derivatives as of December 29, 2018 and December 30, 2017 was: 2018 2017 Current portion of acquisition-related liabilities and Accrued expenses: Contingent consideration $ 1,394 $ 594 Cash flow hedges — 488 Acquisition-related liabilities and Other noncurrent liabilities Contingent consideration $ 5,175 $ 34,301 Cash flow hedges — 492 The fair value accounting guidance establishes the following fair value hierarchy that prioritizes the inputs used to measure fair value: Level 1 — Unadjusted quoted prices for identical assets or liabilities in active markets. Level 2 — Inputs other than Level 1 that are based on observable market data, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in inactive markets, inputs that are observable that are not prices and inputs that are derived from or corroborated by observable markets. Level 3 — Valuations developed from unobservable data, reflecting the Company’s own assumptions, which market participants would use in pricing the asset or liability. The fair value of contingent consideration was based on unobservable, or Level 3, inputs, including projected probability-weighted cash payments and an 10.0% discount rate, which reflects a market discount rate. Changes in fair value may occur as a result of a change in actual or projected cash payments, the probability weightings applied by the Company to projected payments or a change in the discount rate. Significant increases or decreases in any of these inputs in isolation could result in a lower, or higher, fair value measurement. The fair value of the cash flow hedges are based on observable, or Level 2, inputs such as interest rates, bond yields and prices in inactive markets. There were no material adjustments to the fair value of contingent consideration in 2018 or 2017 , or to cash flow hedges in 2018 or 2017 . 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 December 29, 2018 and December 30, 2017 were: December 29, 2018 December 30, 2017 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt(1) $ 1,777,722 $ 1,828,159 $ 1,893,239 $ 1,832,455 Level 3 Current portion of deferred consideration and noncompete obligations(2) 30,376 30,376 10,993 10,993 Long term portion of deferred consideration and noncompete obligations(3) 40,179 40,179 17,938 17,938 ______________________ (1) $6.4 million and $4.8 million included in current portion of debt as of December 29, 2018 and December 30, 2017 , respectively. (2) Included in current portion of acquisition-related liabilities on the consolidated balance sheets. (3) Included in acquisition-related liabilities on the consolidated balance sheets. The fair value of debt was determined based on observable, or Level 2 inputs, such as interest rates, bond yields and quoted prices in inactive markets. The fair values of the deferred consideration and noncompete obligations were determined based on unobservable, or Level 3, inputs, including the cash payment terms in the purchase agreements and a discount rate reflecting the Company’s credit risk. The discount rate used is generally consistent with that used when the obligations were initially recorded. Securities with a maturity of three months or less are considered cash equivalents and the fair value of these assets approximates their carrying value.

Segment Information

Segment Information	12 Months Ended
	Dec. 29, 2018
Segment Reporting Information [Line Items]
Segment Information	Segment Information The Company has three operating segments: West; East; and Cement, which are its reporting segments. These segments are consistent with the Company’s management reporting structure. The operating results of each segment are regularly reviewed and evaluated by the Chief Executive Officer, the Company’s Chief Operating Decision Maker (“CODM”). The CODM primarily evaluates the performance of its segments and allocates resources to them based on a segment profit metric that we call Adjusted EBITDA, which is computed as earnings from continuing operations before interest, taxes, depreciation, depletion, amortization, accretion, share-based compensation, and transaction costs, as well as various other non-recurring, non-cash amounts. The West and East segments have several acquired subsidiaries that are engaged in various activities including quarry mining, aggregate production and contracting. The Cement segment is engaged in the production of Portland cement. Assets employed by each 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 the consolidated financial statements. The following tables display selected financial data for the Company’s reportable business segments as of and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Revenue*: West $ 1,117,066 $ 998,843 $ 813,682 East 703,147 629,919 531,294 Cement 280,789 303,813 281,087 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Intercompany sales are immaterial and the presentation above only reflects sales to external customers. 2018 2017 2016 Income (loss) from operations before taxes $ 96,077 $ (158,200 ) $ 40,827 Interest expense 116,548 108,549 97,536 Depreciation, depletion and amortization 203,305 177,643 147,736 Accretion 1,605 1,875 1,564 IPO/ Legacy equity modification costs — — 37,257 Loss on debt financings 149 4,815 — Tax receivable agreement (benefit) expense (22,684 ) 271,016 14,938 Gain on sale of business (12,108 ) — — Transaction costs 4,238 7,733 6,797 Management fees and expenses — — (1,379 ) Non-cash compensation 25,378 21,140 12,683 Other (6,247 ) 1,206 13,388 Total Adjusted EBITDA $ 406,261 $ 435,777 $ 371,347 Total Adjusted EBITDA by Segment: West $ 188,999 $ 203,590 $ 167,434 East 138,032 139,108 126,007 Cement 111,394 127,547 112,991 Corporate and other (32,164 ) (34,468 ) (35,085 ) Total Adjusted EBITDA $ 406,261 $ 435,777 $ 371,347 2018 2017 2016 Purchases of property, plant and equipment West $ 120,657 $ 83,591 $ 77,335 East 64,384 68,556 45,492 Cement 28,036 35,803 25,408 Total reportable segments 213,077 187,950 148,235 Corporate and other 7,608 6,196 5,248 Total purchases of property, plant and equipment $ 220,685 $ 194,146 $ 153,483 2018 2017 2016 Depreciation, depletion, amortization and accretion: West $ 91,794 $ 71,314 $ 65,345 East 75,433 67,252 51,540 Cement 35,061 38,351 30,006 Total reportable segments 202,288 176,917 146,891 Corporate and other 2,622 2,601 2,409 Total depreciation, depletion, amortization and accretion $ 204,910 $ 179,518 $ 149,300 2018 2017 2016 Total assets: West $ 1,370,501 $ 1,225,463 $ 902,763 East 1,253,640 1,035,609 870,613 Cement 877,586 870,652 868,440 Total reportable segments 3,501,727 3,131,724 2,641,816 Corporate and other 355,914 655,609 139,650 Total $ 3,857,641 $ 3,787,333 $ 2,781,466
Summit Materials, LLC
Segment Reporting Information [Line Items]
Segment Information	Segment Information The Company has three operating segments: West; East; and Cement, which are its reporting segments. These segments are consistent with the Company’s management reporting structure. The operating results of each segment are regularly reviewed and evaluated by the Chief Executive Officer, the Company’s Chief Operating Decision Maker (“CODM”). The CODM primarily evaluates the performance of its segments and allocates resources to them based on a segment profit metric that we call Adjusted EBITDA, which is computed as earnings from continuing operations before interest, taxes, depreciation, depletion, amortization, accretion, share-based compensation, and transaction costs, as well as various other non-recurring, non-cash amounts. The West and East segments have several acquired subsidiaries that are engaged in various activities including quarry mining, aggregate production and contracting. The Cement segment is engaged in the production of Portland cement. Assets employed by each 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 the consolidated financial statements. The following tables display selected financial data for the Company’s reportable business segments as of and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Revenue*: West $ 1,117,066 $ 998,843 $ 813,682 East 703,147 629,919 531,294 Cement 280,789 303,813 281,087 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Intercompany sales are immaterial and the presentation above only reflects sales to external customers. 2018 2017 2016 Income from operations before taxes $ 74,110 $ 113,696 $ 56,805 Interest expense 115,831 107,655 96,483 Depreciation, depletion and amortization 203,305 177,643 147,736 Accretion 1,605 1,875 1,564 IPO/ Legacy equity modification costs — — 37,257 Loss on debt financings 149 4,815 — Gain on sale of business (12,108 ) — — Transaction costs 4,238 7,733 6,797 Management fees and expenses — — (1,379 ) Non-cash compensation 25,378 21,140 12,683 Other (6,247 ) 1,206 13,388 Total Adjusted EBITDA $ 406,261 $ 435,763 $ 371,334 Total Adjusted EBITDA by Segment: West $ 188,999 $ 203,590 $ 167,434 East 138,032 139,108 126,007 Cement 111,394 127,547 112,991 Corporate and other (32,164 ) (34,482 ) (35,098 ) Total Adjusted EBITDA $ 406,261 $ 435,763 $ 371,334 2018 2017 2016 Purchases of property, plant and equipment West $ 120,657 $ 83,591 $ 77,335 East 64,384 68,556 45,492 Cement 28,036 35,803 25,408 Total reportable segments 213,077 187,950 148,235 Corporate and other 7,608 6,196 5,248 Total purchases of property, plant and equipment $ 220,685 $ 194,146 $ 153,483 2018 2017 2016 Depreciation, depletion, amortization and accretion: West $ 91,794 $ 71,314 $ 65,345 East 75,433 67,252 51,540 Cement 35,061 38,351 30,006 Total reportable segments 202,288 176,917 146,891 Corporate and other 2,622 2,601 2,409 Total depreciation, depletion, amortization and accretion $ 204,910 $ 179,518 $ 149,300 2018 2017 2016 Total assets: West $ 1,370,501 $ 1,225,463 $ 902,763 East 1,253,640 1,035,609 870,613 Cement 877,586 870,652 868,440 Total reportable segments 3,501,727 3,131,724 2,641,816 Corporate and other 131,517 372,517 134,604 Total $ 3,633,244 $ 3,504,241 $ 2,776,420

Senior Notes' Guarantor and Non

Senior Notes' Guarantor and Non-Guarantor Financial Information	12 Months Ended
	Dec. 29, 2018
Summit Materials, LLC
Condensed Financial Statements, Captions [Line Items]
Senior Notes' Guarantor and Non-Guarantor Financial Information	Senior Notes’ Guarantor and Non-Guarantor Financial Information Summit LLC’s domestic wholly-owned subsidiary companies other than Finance Corp. are named as guarantors (collectively, the “Guarantors”) of the 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. 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 December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 117,219 $ 8,440 $ 7,719 $ (4,870 ) $ 128,508 Accounts receivable, net — 199,538 15,165 (185 ) 214,518 Intercompany receivables 500,765 624,427 — (1,125,192 ) — Cost and estimated earnings in excess of billings — 17,711 891 — 18,602 Inventories — 210,149 3,702 — 213,851 Other current assets 1,953 11,308 2,800 — 16,061 Total current assets 619,937 1,071,573 30,277 (1,130,247 ) 591,540 Property, plant and equipment, net 13,300 1,709,083 57,749 — 1,780,132 Goodwill — 1,136,785 56,243 — 1,193,028 Intangible assets, net — 18,460 — — 18,460 Other assets 3,292,851 154,080 947 (3,397,794 ) 50,084 Total assets $ 3,926,088 $ 4,089,981 $ 145,216 $ (4,528,041 ) $ 3,633,244 Liabilities and Member’s Interest Current liabilities: Current portion of debt $ 6,354 $ — $ — $ — $ 6,354 Current portion of acquisition-related liabilities — 31,770 — — 31,770 Accounts payable 4,712 92,132 12,349 (185 ) 109,008 Accrued expenses 45,146 57,826 1,927 (4,870 ) 100,029 Intercompany payables 673,175 436,564 15,453 (1,125,192 ) — Billings in excess of costs and estimated earnings — 11,347 493 — 11,840 Total current liabilities 729,387 629,639 30,222 (1,130,247 ) 259,001 Long-term debt 1,807,502 — — — 1,807,502 Acquisition-related liabilities — 45,354 — — 45,354 Other noncurrent liabilities 3,768 226,137 77,368 (171,317 ) 135,956 Total liabilities 2,540,657 901,130 107,590 (1,301,564 ) 2,247,813 Total member's interest 1,385,431 3,188,851 37,626 (3,226,477 ) 1,385,431 Total liabilities and member’s interest $ 3,926,088 $ 4,089,981 $ 145,216 $ (4,528,041 ) $ 3,633,244 Condensed Consolidating Balance Sheets December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 370,741 $ 10,254 $ 14,933 $ (12,372 ) $ 383,556 Accounts receivable, net — 183,139 15,191 — 198,330 Intercompany receivables 573,301 484,747 — (1,058,048 ) — Cost and estimated earnings in excess of billings — 9,264 248 — 9,512 Inventories — 180,283 4,156 — 184,439 Other current assets 1,167 6,354 243 — 7,764 Total current assets 945,209 874,041 34,771 (1,070,420 ) 783,601 Property, plant and equipment, net 9,259 1,569,118 37,047 — 1,615,424 Goodwill — 976,206 61,114 — 1,037,320 Intangible assets, net — 16,833 — — 16,833 Other assets 2,890,674 162,711 1,271 (3,003,593 ) 51,063 Total assets $ 3,845,142 $ 3,598,909 $ 134,203 $ (4,074,013 ) $ 3,504,241 Liabilities and Member’s Interest Current liabilities: Current portion of debt $ 4,765 $ — $ — $ — $ 4,765 Current portion of acquisition-related liabilities — 11,587 — — 11,587 Accounts payable 3,976 89,912 6,749 — 100,637 Accrued expenses 47,047 79,372 2,227 (12,372 ) 116,274 Intercompany payables 684,057 369,918 4,073 (1,058,048 ) — Billings in excess of costs and estimated earnings — 15,349 401 — 15,750 Total current liabilities 739,845 566,138 13,450 (1,070,420 ) 249,013 Long-term debt 1,810,833 — — — 1,810,833 Acquisition-related liabilities — 52,239 — — 52,239 Other noncurrent liabilities 2,870 193,801 75,209 (171,318 ) 100,562 Total liabilities 2,553,548 812,178 88,659 (1,241,738 ) 2,212,647 Total member's interest 1,291,594 2,786,731 45,544 (2,832,275 ) 1,291,594 Total liabilities and member’s interest $ 3,845,142 $ 3,598,909 $ 134,203 $ (4,074,013 ) $ 3,504,241 Condensed Consolidating Statements of Operations and Comprehensive Loss Year Ended December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 2,018,428 $ 88,658 $ (6,084 ) $ 2,101,002 Cost of revenue (excluding items shown separately below) — 1,416,222 65,641 (6,084 ) 1,475,779 General and administrative expenses 62,376 184,917 10,554 — 257,847 Depreciation, depletion, amortization and accretion 2,622 197,406 4,882 — 204,910 Operating (loss) income (64,998 ) 219,883 7,581 — 162,466 Other (income) loss, net (249,204 ) (14,643 ) 823 247,657 (15,367 ) Interest expense (income) 118,857 (7,818 ) 4,792 — 115,831 Gain on sale of business — (12,108 ) — — (12,108 ) Income from operations before taxes 65,349 254,452 1,966 (247,657 ) 74,110 Income tax expense 1,512 8,226 535 — 10,273 Net income attributable to member of Summit Materials, LLC $ 63,837 $ 246,226 $ 1,431 $ (247,657 ) $ 63,837 Comprehensive income attributable to member of Summit Materials, LLC $ 57,356 $ 243,359 $ 10,779 $ (254,138 ) $ 57,356 Condensed Consolidating Statements of Operations and Comprehensive Loss Year ended December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 1,854,434 $ 84,020 $ (5,879 ) $ 1,932,575 Cost of revenue (excluding items shown separately below) — 1,227,037 60,619 (5,879 ) 1,281,777 General and administrative expenses 63,954 178,023 8,426 — 250,403 Depreciation, depletion, amortization and accretion 2,601 172,738 4,179 — 179,518 Operating (loss) income (66,555 ) 276,636 10,796 — 220,877 Other income, net (307,876 ) (1,925 ) (533 ) 309,860 (474 ) Interest expense (income) 105,735 (2,415 ) 4,335 — 107,655 Income from operations before taxes 135,586 280,976 6,994 (309,860 ) 113,696 Income tax expense (benefit) 1,518 (23,774 ) 1,911 — (20,345 ) Net income 134,068 304,750 5,083 (309,860 ) 134,041 Net loss attributable to noncontrolling interest — — — (27 ) (27 ) Net income attributable to member of Summit Materials, LLC $ 134,068 $ 304,750 $ 5,083 $ (309,833 ) $ 134,068 Comprehensive income (loss) attributable to member of Summit Materials, LLC $ 144,377 $ 302,209 $ (2,685 ) $ (299,524 ) $ 144,377 Condensed Consolidating Statements of Operations and Comprehensive Loss Year ended December 31, 2016 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 1,586,858 $ 47,064 $ (7,859 ) $ 1,626,063 Cost of revenue (excluding items shown separately below) — 1,047,120 32,531 (7,859 ) 1,071,792 General and administrative expenses 91,533 152,402 6,374 — 250,309 Depreciation, depletion, amortization and accretion 2,410 142,773 4,117 — 149,300 Operating (loss) income (93,943 ) 244,563 4,042 — 154,662 Other (income) loss, net (239,082 ) 1,908 (326 ) 238,874 1,374 Interest expense 83,068 9,956 3,459 — 96,483 Income from continuing operations before taxes 62,071 232,699 909 (238,874 ) 56,805 Income tax (benefit) expense — (5,551 ) 269 — (5,282 ) Net income 62,071 238,250 640 (238,874 ) 62,087 Net income attributable to noncontrolling interest — — — 16 16 Net income attributable to member of Summit Materials, LLC $ 62,071 $ 238,250 $ 640 $ (238,890 ) $ 62,071 Comprehensive income attributable to member of Summit Materials, LLC $ 63,093 $ 239,353 $ (1,485 ) $ (237,868 ) $ 63,093 Condensed Consolidating Statements of Cash Flows For the year ended December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (142,315 ) $ 340,401 $ 11,282 $ — $ 209,368 Cash flow from investing activities: Acquisitions, net of cash acquired — (246,017 ) — — (246,017 ) Purchase of property, plant and equipment (7,607 ) (188,435 ) (24,643 ) — (220,685 ) Proceeds from the sale of property, plant, and equipment — 21,263 372 — 21,635 Proceeds from the sale of a business — 21,564 — — 21,564 Other — 3,804 — — 3,804 Net cash used for investing activities (7,607 ) (387,821 ) (24,271 ) — (419,699 ) Cash flow from financing activities: Proceeds from investment by member (146,533 ) 162,148 — — 15,615 Net proceeds from debt issuance 64,500 — — — 64,500 Loans received from and payments made on loans from other Summit Companies 51,696 (65,845 ) 6,647 7,502 — Payments on long-term debt (69,265 ) (15,662 ) (115 ) — (85,042 ) Payments on acquisition-related liabilities — (34,004 ) — — (34,004 ) Debt issuance costs (550 ) — — — (550 ) Distributions from partnership (2,569 ) — — — (2,569 ) Other (879 ) (1,031 ) (33 ) — (1,943 ) Net cash (used in) provided by financing activities (103,600 ) 45,606 6,499 7,502 (43,993 ) Impact of cash on foreign currency — — (724 ) — (724 ) Net decrease in cash (253,522 ) (1,814 ) (7,214 ) 7,502 (255,048 ) Cash — Beginning of period 370,741 10,254 14,933 (12,372 ) 383,556 Cash — End of period $ 117,219 $ 8,440 $ 7,719 $ (4,870 ) $ 128,508 Condensed Consolidating Statements of Cash Flows For the year ended December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (127,102 ) $ 392,316 $ 29,918 $ — $ 295,132 Cash flow from investing activities: Acquisitions, net of cash acquired (24,538 ) (324,892 ) (25,500 ) — (374,930 ) Purchase of property, plant and equipment (6,196 ) (182,295 ) (5,655 ) — (194,146 ) Proceeds from the sale of property, plant, and equipment — 16,822 250 — 17,072 Other — (471 ) — — (471 ) Net cash used for investing activities (30,734 ) (490,836 ) (30,905 ) — (552,475 ) Cash flow from financing activities: Proceeds from investment by member 40,913 252,911 10,717 — 304,541 Capital issuance costs (627 ) — — — (627 ) Net proceeds from debt issuance 302,000 — — — 302,000 Loans received from and payments made on loans from other Summit Companies 119,858 (108,026 ) (10,126 ) (1,706 ) — Payments on long-term debt (8,463 ) (7,967 ) (8 ) — (16,438 ) Purchase of noncontrolling interests — (532 ) — — (532 ) Payments on acquisition-related liabilities — (32,150 ) — — (32,150 ) Financing costs (6,416 ) — — — (6,416 ) Distributions from partnership (51,986 ) — — — (51,986 ) Other (564 ) (282 ) (20 ) — (866 ) Net cash provided by financing activities 394,715 103,954 563 (1,706 ) 497,526 Impact of cash on foreign currency — — 701 — 701 Net increase in cash 236,879 5,434 277 (1,706 ) 240,884 Cash — Beginning of period 133,862 4,820 14,656 (10,666 ) 142,672 Cash — End of period $ 370,741 $ 10,254 $ 14,933 $ (12,372 ) $ 383,556 Condensed Consolidating Statements of Cash Flows For the year ended December 31, 2016 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (132,328 ) $ 373,588 $ 3,617 $ — $ 244,877 Cash flow from investing activities: Acquisitions, net of cash acquired (42,844 ) (294,114 ) — — (336,958 ) Purchase of property, plant and equipment (5,247 ) (146,336 ) (1,900 ) — (153,483 ) Proceeds from the sale of property, plant, and equipment — 16,606 262 — 16,868 Other — 2,921 — — 2,921 Net cash used for investing activities (48,091 ) (420,923 ) (1,638 ) — (470,652 ) Cash flow from financing activities: Proceeds from investment by member (502,140 ) 529,517 — — 27,377 Capital issuance costs (136 ) — — — (136 ) Net proceeds from debt issuance 354,000 — — — 354,000 Loans received from and payments made on loans from other Summit Companies 440,738 (442,072 ) 400 934 — Payments on long-term debt (110,500 ) (10,202 ) — — (120,702 ) Payments on acquisition-related liabilities (400 ) (29,140 ) — — (29,540 ) Financing costs (5,801 ) — — — (5,801 ) Distributions from partnership (42,192 ) — — — (42,192 ) Other — (16 ) — — (16 ) Net cash provided by financing activities 133,569 48,087 400 934 182,990 Impact of cash on foreign currency — — 69 — 69 Net (decrease) increase in cash (46,850 ) 752 2,448 934 (42,716 ) Cash — Beginning of period 180,712 4,068 12,208 (11,600 ) 185,388 Cash — End of period $ 133,862 $ 4,820 $ 14,656 $ (10,666 ) $ 142,672

Supplementary Data (Unaudited)

Supplementary Data (Unaudited)	12 Months Ended
	Dec. 29, 2018
Quarterly Financial Information [Line Items]
Supplementary Data (Unaudited)	Supplementary Data (Unaudited) Supplemental financial information (unaudited) by quarter is shown below for the years ended December 29, 2018 and December 30, 2017 . 2018 2017 4Q 3Q 2Q 1Q 4Q 3Q 2Q 1Q Net revenue $ 445,090 $ 625,017 $ 549,235 $ 289,916 $ 440,610 $ 574,387 $ 478,368 $ 259,044 Operating income (loss) 28,545 108,167 77,279 (51,525 ) 57,306 113,911 82,444 (32,784 ) Net income (loss) (18,627 ) 73,992 36,913 (55,948 ) 44,510 84,287 52,088 (55,108 ) Net income (loss) attributable to Summit Inc. (19,163 ) 71,289 35,509 (53,729 ) 43,010 81,264 50,000 (52,444 ) Basic earnings per share attributable to Summit Inc. $ (0.17 ) $ 0.64 $ 0.32 $ (0.49 ) $ 0.39 $ 0.74 $ 0.46 $ (0.49 ) Diluted earnings per share attributable to Summit Inc. (0.17 ) 0.64 0.32 (0.49 ) 0.38 0.73 0.46 (0.49 ) SUMMIT MATERIALS, LLC AND SUBSIDIARIES CONSOLIDATED FINANCIAL STATEMENTS The consolidated financial statements and notes thereto for Summit Materials, LLC and subsidiaries are included as Exhibit 99.1 to this Amendment No. 1 and are incorporated by reference herein.
Summit Materials, LLC
Quarterly Financial Information [Line Items]
Supplementary Data (Unaudited)	Supplementary Data (Unaudited) Supplemental financial information (unaudited) by quarter is as follows for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 4Q 3Q 2Q 1Q 4Q 3Q 2Q 1Q Net revenue $ 445,090 $ 625,017 $ 549,235 $ 289,916 $ 440,610 $ 574,387 $ 478,368 $ 259,044 Operating income (loss) 28,545 108,167 77,279 (51,525 ) 57,306 113,911 82,444 (32,784 ) Net income (loss) (4,596 ) 90,427 46,602 (68,596 ) 52,435 82,633 53,827 (54,854 )

Summary of Organization and S_2

Summary of Organization and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 29, 2018
Company Information
Principles of Consolidation	Principles of Consolidation —The consolidated financial statements include the accounts of Summit Inc. and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. As a result of the Reorganization, Summit Holdings became a variable interest entity over which Summit Inc. has 100% voting power and control and for which Summit Inc. has the obligation to absorb losses and the right to receive benefits. 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 last occurred in 2015. For a summary of the changes in Summit Inc.’s ownership of Summit Holdings, see Note 11, Stockholders’ Equity. The Company attributes consolidated stockholders’ equity and net income separately to the controlling and noncontrolling interests. The Company accounts for investments in entities for which it has an ownership of 20% to 50% using the equity method of accounting.
Use of Estimates	Use of Estimates —Preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, the tax receivable agreement (“TRA”) liability, 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. 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 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas 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 a significant concentration of credit exists with respect to any individual customer or group of customers.
Accounts Receivable	Accounts Receivable —Accounts receivable are stated at the amount management expects to collect from outstanding balances. Management provides for probable uncollectible amounts through a charge to earnings and a credit to a valuation allowance based on its assessment of the collectability of individual accounts. In establishing the allowance, management considers historical losses adjusted to take into account current market conditions and its customers’ financial condition, the amount of receivables in dispute, the current receivables aging and current payment terms. Balances that remain outstanding after reasonable collection efforts are exercised are written off through a charge to the valuation allowance. The balances billed but not paid by customers, pursuant to retainage provisions included in contracts, are generally due upon completion of the contracts.
Revenue Recognition	Revenue Recognition —We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental. Products We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped. Aggregates and cement products are sold point-of-sale through purchase orders. When the product is sold on account, collectability typically occurs 30 to 60 days after the sale. Revenue is recognized when cash is received from the customer at the point of sale or when the products are delivered or collected on site. There are no other timing implications that will create a contract asset or liability, and contract modifications are unlikely given the timing and nature of the transaction. Material sales are likely to have multiple performance obligations if the product is sold with delivery. In these instances, delivery most often occurs on the same day as the control of the product transfers to the customer. As a result, even in the case of multiple performance obligations, the performance obligations are satisfied concurrently and revenue is recognized simultaneously. Services We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants, and underground storage space rental. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations. Collectability of service contracts is due reasonably after certain milestones in the contract are performed. Milestones vary by project, but are typically calculated using monthly progress based on the percentage of completion or a customer’s engineer review of progress. The majority of the time, collection occurs within 90 days of billing and cash is received within the same fiscal year as services performed. On most projects, the customer will withhold a portion of the invoice for retainage, which may last longer than a year depending on the job. Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified. The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the year ended December 29, 2018 . We recognize claims when the amount of the claim can be estimated reliably and its realization is probable. In evaluating these criteria, we consider the contractual basis for the claim, the cause of any additional costs incurred, the reasonableness of those costs and the objective evidence available to support the claim. When the contract includes variable consideration, we estimate the amount of consideration to which we will be entitled in exchange for transferring the promised goods or services to a customer. The amount of estimated variable consideration included in the transaction price is the amount for which it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Types of variable consideration include, but are not limited to, liquidated damages and other performance penalties and production and placement bonuses. The majority of contract modifications relate to the original contract and are often an extension of the original performance obligation. Predominately, modifications are not distinct from the terms in the original contract; therefore, they are considered part of a single performance obligation. We account for the modification using a cumulative catch-up adjustment. However, there are instances where goods or services in a modification are distinct from those transferred prior to the modification. In these situations, we account for the modifications as either a separate contract or prospectively depending on the facts and circumstances of the modification. Generally, construction contracts contain mobilization costs which are categorized as costs to fulfill a contract. These costs are excluded from any measure of progress toward contract fulfillment. These costs do not result in the transfer of control of a good or service to the customer and are amortized over the life of the contract. Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis.
Inventories	Inventories —Inventories consist of stone that has been removed from quarries and processed for future sale, cement, raw materials and finished concrete blocks. Inventories are valued at the lower of cost or market and are accounted for on a first-in first-out basis or an average cost basis. If items become obsolete or otherwise unusable or if quantities exceed what is projected to be sold within a reasonable period of time, they will be charged to costs of production in the period that the items are designated as obsolete or excess inventory. Stripping costs are costs of removing overburden and waste material to access aggregate materials and are expensed as incurred.
Property, Plant and Equipment, net	Property, Plant and Equipment, net —Property, plant and equipment are recorded at cost, less accumulated depreciation, depletion and amortization. Expenditures for additions and improvements that significantly add to the productive capacity or extend the useful life of an asset are capitalized. Repair and maintenance costs that do not substantially expand productive capacity or extend the life of property, plant and equipment are expensed as incurred. Landfill airspace is included in property, plant and equipment at cost and is amortized based on the portion of the airspace used during the period compared to the gross estimated value of available airspace, which is updated periodically as circumstances dictate. Management reassesses the landfill airspace capacity with any changes in value recorded in cost of revenue. Capitalized landfill costs include expenditures for the acquisition of land and related airspace, engineering and permitting costs, cell construction costs and direct site improvement costs. Upon disposal of an asset, the cost and related accumulated depreciation are removed from the Company’s accounts and any gain or loss is included in general and administrative expenses. The Company reviews the carrying value of property, plant and equipment for impairment whenever events or circumstances indicate that the carrying value of an asset may not be recoverable from the estimated future cash flows expected to result from its use and eventual disposition. Such indicators may include, among others, deterioration in general economic conditions, adverse changes in the markets in which an entity operates, increases in input costs that have a negative effect on earnings and cash flows or a trend of negative or declining cash flows over multiple periods. Property, plant and equipment is tested for impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. As a result, the property, plant and equipment impairment test is at a significantly lower level than the level at which goodwill is tested for impairment. In markets where the Company does not produce downstream products, such as ready-mix concrete, asphalt paving mix and paving and related services, the lowest level of largely independent identifiable cash flows is at the individual aggregates operation or a group of aggregates operations collectively serving a local market or the cement operations. Conversely, in vertically-integrated markets, the cash flows of the downstream and upstream businesses are not largely independently identifiable and the vertically-integrated operations are considered the lowest level of largely independent identifiable cash flows.
Accrued Mining and Landfill Reclamation	Accrued Mining and Landfill Reclamation —The mining reclamation reserve and financial commitments for landfill closure and post-closure activities are based on management’s estimate of future cost requirements to reclaim property at both currently operating and closed sites. Estimates of these obligations have been developed based on management’s interpretation of current requirements and proposed regulatory changes and are intended to approximate fair value. Costs are estimated in current dollars, inflated until the expected time of payment, and then discounted back to present value using a credit-adjusted, risk-free rate on obligations of similar maturity, adjusted to reflect the Company’s credit rating. Changes in the credit-adjusted, risk-free rate do not change recorded liabilities. However, subsequent increases in the recognized obligations are measured using a current credit-adjusted, risk-free rate. Decreases in the recognized obligations are measured at the initial credit-adjusted, risk-free rate. Significant changes in inflation rates or the amount or timing of future cost estimates typically result in both (1) a current adjustment to the recorded liability (and corresponding adjustment to the asset) and (2) a change in accretion of the liability and depreciation of the asset to be recorded prospectively over the remaining capacity of the unmined quarry or landfill.
Goodwill	Goodwill —Goodwill represents the purchase price paid in excess of the fair value of net tangible and intangible assets acquired. Goodwill recorded in connection with the Company’s acquisitions is primarily attributable to the expected profitability, assembled workforces of the acquired businesses and the synergies expected to arise after the Company’s acquisition of those businesses. Goodwill is not amortized, but is tested annually for impairment as of the first day of the fourth quarter and at any time that events or circumstances indicate that goodwill may be impaired. A qualitative approach may first be applied to determine whether it is more likely than not that the estimated fair value of a reporting unit is less than its carrying amount. If, as a result of the qualitative assessment, it is determined that an impairment is more likely than not, the two-step quantitative impairment test is then performed, otherwise further analysis is not required. The two-step impairment test first identifies potential goodwill impairment for each reporting unit and then, if necessary, measures the amount of the impairment loss.
Income Taxes	Income Taxes —Summit Inc. is a corporation subject to income taxes in the United States. Certain subsidiaries, including Summit Holdings, or subsidiary groups of the Company are taxable separate from Summit Inc. The provisions, or Summit Inc.’s proportional share of the provision, are included in the Company’s consolidated financial statements. The Company’s deferred income tax assets and liabilities are computed for differences between the tax basis and financial statement amounts that will result in taxable or deductible amounts in the future. The computed deferred balances are based on enacted tax laws and applicable rates for the periods in which the differences are expected to affect taxable income. A valuation allowance is recognized for deferred tax assets if it is more likely than not that some portion or all of the net deferred tax assets will not be realized. In making such a determination, all available positive and negative evidence is considered, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines it would be able to realize its deferred tax assets for which a valuation allowance had been recorded then an adjustment would be made to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company evaluates the tax positions taken on income tax returns that remain open and positions expected to be taken on the current year tax returns to identify uncertain tax positions. Unrecognized tax benefits on uncertain tax positions are recorded on the basis of a two-step process in which (1) the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, the largest amount of tax benefit that is more than 50 percent likely to be realized is recognized. Interest and penalties related to unrecognized tax benefits are recorded in income tax benefit.
Tax Receivable Agreement	Tax Receivable Agreement — When Summit Inc. purchases LP Units for cash or LP Units are exchanged for shares of Class A common stock, this results in increases in Summit Inc.’s share of the tax basis of the tangible and intangible assets, which increases the tax depreciation and amortization deductions that otherwise would not have been available to Summit Inc. These increases in tax basis and tax depreciation and amortization deductions are expected to reduce the amount of cash taxes that we would otherwise be required to pay in the future. Prior to our IPO, we entered into a TRA with the pre-IPO owners that require us to pay the pre-IPO owners 85% of the amount of cash savings, if any, in U.S. federal, state, and local income tax that we actually realize as a result of these exchanges. These benefits include (1) increases in the tax basis of tangible and intangible assets of Summit Holdings and certain other tax benefits related to entering into the TRA, (2) tax benefits attributable to payments under the TRA, or (3) under certain circumstances such as an early termination of the TRA, we are deemed to realize, as a result of the increases in tax basis in connection with exchanges by the pre-IPO owners described above and certain other tax benefits attributable to payments under the TRA. As noted above, we periodically evaluate the realizability of the deferred tax assets resulting from the exchange of LP Units for Class A common stock. If the deferred tax assets are determined to be realizable, we then assess whether payment of amounts under the TRA have become probable. If so, we record a TRA liability equal to 85% of such deferred tax assets. In subsequent periods, we assess the realizability of all of our deferred tax assets subject to the TRA. Should we determine a deferred tax asset with a valuation allowance is realizable in a subsequent period, the related valuation allowance will be released and consideration of a corresponding TRA liability will be assessed. The realizability of deferred tax assets, including those subject to the TRA, is dependent upon the generation of future taxable income during the periods in which those deferred tax assets become deductible and consideration of prudent and feasible tax-planning strategies. The measurement of the TRA liability is accounted for as a contingent liability. Therefore, once we determine that a payment to a pre-IPO owner has become probable and can be estimated, the estimate of payment will be accrued.
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 shares of Class A common stock 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 stock has no economic value, those shares are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the shares of Class A common stock are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic earnings per share.
New Accounting Standards	New Accounting Standards — In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers , which 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. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. We adopted this new standard in January 2018 using the modified retrospective approach. The adoption of this new ASU did not have a material impact on our consolidated financial results. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will result in lessees recognizing most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018, are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have compiled our leases, and currently estimate that we will record additional right of use assets and liabilities of approximately $30 to $40 million beginning in 2019. We plan to adopt this ASU, as amended, using the modified retrospective approach. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business, which narrows the definition of a business. This ASU provides a screen to determine whether a group of assets constitutes a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated as acquisitions. If the screen is not met, this ASU (1) requires that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create an output and (2) removes the evaluation of whether a market participant could replace missing elements. Although outputs are not required for a set to be a business, outputs generally are a key element of a business; therefore, the FASB has developed more stringent criteria for sets without outputs. We adopted this ASU beginning in 2018. The adoption of this ASU did not have a material impact on the consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements.
Summit Materials, LLC
Company Information
Principles of Consolidation	Principles of Consolidation –The consolidated financial statements include the accounts of Summit LLC and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. The Company attributes consolidated member’s interest and net income separately to the controlling and noncontrolling interests. Noncontrolling interests in consolidated subsidiaries represent a 20% ownership in Ohio Valley Asphalt, LLC and, prior to the initial public offering (“IPO”) and concurrent purchase of the noncontrolling interests Continental Cement Company, L.L.C. (“Continental Cement”), a 30% redeemable ownership in Continental Cement. The Company accounts for investments in entities for which it has an ownership of 20% to 50% using the equity method of accounting. In the fourth quarter of 2017, we purchased the remaining noncontrolling interest in Ohio Valley Asphalt, LLC. 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 occurred in 2015.
Use of Estimates	Use of Estimates — Preparation of these consolidated financial statements in conformity with U.S. generally accepted accounting principles (“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, valuation of deferred tax assets, 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. 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 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas 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 a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in 2018 , 2017 or 2016 .
Accounts Receivable	Accounts Receivable —Accounts receivable are stated at the amount management expects to collect from outstanding balances. Management provides for probable uncollectible amounts through a charge to earnings and a credit to a valuation allowance based on its assessment of the collectability of individual accounts. In establishing the allowance, management considers historical losses adjusted to take into account current market conditions and its customers’ financial condition, the amount of receivables in dispute, the current receivables aging and current payment terms. Balances that remain outstanding after reasonable collection efforts are exercised are written off through a charge to the valuation allowance. The balances billed but not paid by customers, pursuant to retainage provisions included in contracts, are generally due upon completion of the contracts.
Revenue Recognition	Revenue Recognition —
Inventories	Inventories —Inventories consist of stone that has been removed from quarries and processed for future sale, cement, raw materials and finished concrete blocks. Inventories are valued at the lower of cost or market and are accounted for on a first-in first-out basis or an average cost basis. If items become obsolete or otherwise unusable or if quantities exceed what is projected to be sold within a reasonable period of time, they will be charged to costs of production in the period that the items are designated as obsolete or excess inventory. Stripping costs are costs of removing overburden and waste material to access aggregate materials and are expensed as incurred.
Property, Plant and Equipment, net	Property, Plant and Equipment, net —Property, plant and equipment are recorded at cost, less accumulated depreciation, depletion and amortization. Expenditures for additions and improvements that significantly add to the productive capacity or extend the useful life of an asset are capitalized. Repair and maintenance costs that do not substantially expand productive capacity or extend the life of property, plant and equipment are expensed as incurred. Landfill airspace is included in property, plant and equipment at cost and is amortized based on the portion of the airspace used during the period compared to the gross estimated value of available airspace, which is updated periodically as circumstances dictate. Management reassesses the landfill airspace capacity with any changes in value recorded in cost of revenue. Capitalized landfill costs include expenditures for the acquisition of land and related airspace, engineering and permitting costs, cell construction costs and direct site improvement costs. Upon disposal of an asset, the cost and related accumulated depreciation are removed from the Company’s accounts and any gain or loss is included in general and administrative expenses. The Company reviews the carrying value of property, plant and equipment for impairment whenever events or circumstances indicate that the carrying value of an asset may not be recoverable from the estimated future cash flows expected to result from its use and eventual disposition. Such indicators may include, among others, deterioration in general economic conditions, adverse changes in the markets in which an entity operates, increases in input costs that have a negative effect on earnings and cash flows or a trend of negative or declining cash flows over multiple periods. Property, plant and equipment is tested for impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. As a result, the property, plant and equipment impairment test is at a significantly lower level than the level at which goodwill is tested for impairment. In markets where the Company does not produce downstream products, such as ready-mix concrete, asphalt paving mix and paving and related services, the lowest level of largely independent identifiable cash flows is at the individual aggregates operation or a group of aggregates operations collectively serving a local market or the cement operations. Conversely, in vertically-integrated markets, the cash flows of the downstream and upstream businesses are not largely independently identifiable and the vertically-integrated operations are considered the lowest level of largely independent identifiable cash flows.
Accrued Mining and Landfill Reclamation	Accrued Mining and Landfill Reclamation —The mining reclamation reserve and financial commitments for landfill closure and post-closure activities are based on management’s estimate of future cost requirements to reclaim property at both currently operating and closed sites. Estimates of these obligations have been developed based on management’s interpretation of current requirements and proposed regulatory changes and are intended to approximate fair value. Costs are estimated in current dollars, inflated until the expected time of payment, and then discounted back to present value using a credit-adjusted, risk-free rate on obligations of similar maturity, adjusted to reflect the Company’s credit rating. Changes in the credit-adjusted, risk-free rate do not change recorded liabilities. However, subsequent increases in the recognized obligations are measured using a current credit-adjusted, risk-free rate. Decreases in the recognized obligations are measured at the initial credit-adjusted, risk-free rate. Significant changes in inflation rates or the amount or timing of future cost estimates typically result in both (1) a current adjustment to the recorded liability (and corresponding adjustment to the asset) and (2) a change in accretion of the liability and depreciation of the asset to be recorded prospectively over the remaining capacity of the unmined quarry or landfill.
Goodwill	Goodwill —Goodwill represents the purchase price paid in excess of the fair value of net tangible and intangible assets acquired. Goodwill recorded in connection with the Company’s acquisitions is primarily attributable to the expected profitability, assembled workforces of the acquired businesses and the synergies expected to arise after the Company’s acquisition of those businesses. Goodwill is not amortized, but is tested annually for impairment as of the first day of the fourth quarter and at any time that events or circumstances indicate that goodwill may be impaired. A qualitative approach may first be applied to determine whether it is more likely than not that the estimated fair value of a reporting unit is less than its carrying amount. If, as a result of the qualitative assessment, it is determined that an impairment is more likely than not, the two-step quantitative impairment test is then performed, otherwise further analysis is not required. The two-step impairment test first identifies potential goodwill impairment for each reporting unit and then, if necessary, measures the amount of the impairment loss.
Income Taxes	Income Taxes —As a limited liability company, the Company’s federal and state income tax attributes are generally passed to its member. However, certain subsidiaries, or subsidiary groups, of the Company are taxable entities subject to income taxes in the United States and Canada, the provisions for which are included in the consolidated financial statements. Significant judgments and estimates are required in the determination of the consolidated income tax expense. The Company’s deferred income tax assets and liabilities are computed for differences between the tax basis and financial statement amounts that will result in taxable or deductible amounts in the future. The computed deferred balances are based on enacted tax laws and applicable rates for the periods in which the differences are expected to affect taxable income. A valuation allowance is recognized for deferred tax assets if it is more likely than not that some portion or all of the net deferred tax assets will not be realized. In making such a determination, all available positive and negative evidence is considered, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines it would be able to realize its deferred tax assets for which a valuation allowance had been recorded then an adjustment would be made to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company evaluates the tax positions taken on income tax returns that remain open and positions expected to be taken on the current year tax returns to identify uncertain tax positions. Unrecognized tax benefits on uncertain tax positions are recorded on the basis of a two-step process in which (1) the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, the largest amount of tax benefit that is more than 50 percent likely to be realized is recognized. Interest and penalties related to unrecognized tax benefits are recorded in income tax benefit.
New Accounting Standards	New Accounting Standards — In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers , which 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. In July 2015, the FASB postponed the effective date of the new revenue standard by one year to the first quarter of 2018. We adopted this new standard in January 2018 using the modified retrospective approach. The adoption of this new ASU did not have a material impact on our consolidated financial results. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will result in lessees recognizing most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018, are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have compiled our leases, and currently estimate that we will record additional right of use assets and liabilities of approximately $30 to $40 million beginning in 2019. We plan to adopt this ASU, as amended, using the modified retrospective approach. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business, which narrows the definition of a business. This ASU provides a screen to determine whether a group of assets constitutes a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated as acquisitions. If the screen is not met, this ASU (1) requires that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create an output and (2) removes the evaluation of whether a market participant could replace missing elements. Although outputs are not required for a set to be a business, outputs generally are a key element of a business; therefore, the FASB has developed more stringent criteria for sets without outputs. We adopted this ASU beginning in 2018. The adoption of this ASU did not have a material impact on the consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 29, 2018
Summary of Acquisitions by Region	The following table summarizes the Company’s acquisitions by region and year: 2018 2017 2016 West 5 6 3 East (1) 7 8 5 Cement — — 1 ______________________ (1) In addition, the Company acquired certain assets of a small ready-mix concrete operation in the second quarter of 2018.
Summary of Assets Acquired and Liabilities Assumed	The table below summarizes aggregated information regarding the fair values of the assets acquired and liabilities assumed as of the respective acquisition dates. Information related to the 2018 acquisitions is shown on an aggregated basis as the acquisitions were not material individually, or collectively. 2018 2017 Financial assets $ 14,769 $ 31,615 Inventories 18,313 8,300 Property, plant and equipment 124,957 160,975 Intangible assets 3,175 161 Other assets 1,539 4,200 Financial liabilities (13,529 ) (15,501 ) Other long-term liabilities (8,125 ) (17,610 ) Net assets acquired 141,099 172,140 Goodwill 154,120 247,536 Purchase price 295,219 419,676 Acquisition-related liabilities (49,202 ) (43,452 ) Other — (1,294 ) Net cash paid for acquisitions $ 246,017 $ 374,930
Schedule of remaining payments under noncompete and deferred consideration agreements	The remaining payments due under these noncompete and deferred consideration agreements are as follows: 2019 $ 32,960 2020 31,745 2021 9,705 2022 3,411 2023 2,657 Thereafter 9,640 Total scheduled payments 90,118 Present value adjustments (12,949 ) Total noncompete obligations and deferred consideration $ 77,169
Summit Materials, LLC
Summary of Acquisitions by Region	The following table summarizes the Company’s acquisitions by region and year: 2018 2017 2016 West 5 6 3 East (1) 7 8 5 Cement — — 1 ______________________ (1) In addition, the Company acquired certain assets of a small ready-mix concrete operation in the second quarter of 2018.
Summary of Assets Acquired and Liabilities Assumed	The table below summarizes aggregated information regarding the fair values of the assets acquired and liabilities assumed as of the respective acquisition dates. Information related to the 2018 acquisitions is shown on an aggregated basis as the acquisitions were not material individually, or collectively. 2018 2017 Financial assets $ 14,769 $ 31,615 Inventories 18,313 8,300 Property, plant and equipment 124,957 160,975 Intangible assets 3,175 161 Other assets 1,539 4,200 Financial liabilities (13,529 ) (15,501 ) Other long-term liabilities (8,125 ) (17,610 ) Net assets acquired 141,099 172,140 Goodwill 154,120 247,536 Purchase price 295,219 419,676 Acquisition-related liabilities (49,202 ) (43,452 ) Other — (1,294 ) Net cash paid for acquisitions $ 246,017 $ 374,930
Schedule of remaining payments under noncompete and deferred consideration agreements	The remaining payments due under these noncompete and deferred consideration agreements are as follows: 2019 $ 30,460 2020 29,245 2021 7,205 2022 3,411 2023 2,657 Thereafter 9,640 Total scheduled payments 82,618 Present value adjustments (12,063 ) Total noncompete obligations and deferred consideration $ 70,555

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 29, 2018
Goodwill by Reportable Segment and in Total	The following table presents goodwill by reportable segments and in total: West East Cement Total Balance, December 31, 2016 $ 334,257 $ 243,417 $ 204,538 $ 782,212 Acquisitions 187,883 61,957 118 249,958 Foreign currency translation adjustments 4,150 — — 4,150 Balance, December 30, 2017 $ 526,290 $ 305,374 $ 204,656 $ 1,036,320 Acquisitions (1) 59,148 101,431 — 160,579 Foreign currency translation adjustments (4,871 ) — — (4,871 ) Balance, December 29, 2018 $ 580,567 $ 406,805 $ 204,656 $ 1,192,028 ______________________ (1) Reflects goodwill from 2018 acquisitions and working capital adjustments from prior year acquisitions.
Summit Materials, LLC
Goodwill by Reportable Segment and in Total	The following table presents goodwill by reportable segments and in total: West East Cement Total Balance, December 31, 2016 $ 334,257 $ 243,417 $ 204,538 $ 782,212 Acquisitions 188,883 61,957 118 250,958 Foreign currency translation adjustments 4,150 — — 4,150 Balance, December 30, 2017 $ 527,290 $ 305,374 $ 204,656 $ 1,037,320 Acquisitions (1) 59,148 101,431 — 160,579 Foreign currency translation adjustments (4,871 ) — — (4,871 ) Balance, December 29, 2018 $ 581,567 $ 406,805 $ 204,656 $ 1,193,028 ______________________ (1) Reflects goodwill from 2018 acquisitions and working capital adjustments from prior year acquisitions.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 29, 2018
Revenue from External Customer [Line Items]
Summary of Revenue by Products	Revenue by product for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 consisted of the following: 2018 2017 2016 Revenue by product*: Aggregates $ 373,824 $ 313,383 $ 264,609 Cement 258,876 282,041 250,349 Ready-mix concrete 584,114 492,302 395,917 Asphalt 301,247 285,653 239,419 Paving and related services 379,540 371,763 304,041 Other 203,401 187,433 171,728 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Revenue from the liquid asphalt terminals is included in asphalt revenue.
Summary of Contract Assets and Liabilities	The following table outlines the significant changes in contract assets and contract liability balances from December 30, 2017 to December 29, 2018 . Also included in the table is the net change in the estimate as a percentage of aggregate revenue for such contracts: Costs and estimated Billings in excess earnings in of costs and excess of billings estimated earnings Balance—December 30, 2017 $ 9,512 $ 15,750 Changes in revenue billed, contract price or cost estimates 8,702 (5,052 ) Acquisitions 483 1,179 Other (95 ) (37 ) Balance—December 29, 2018 $ 18,602 $ 11,840
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Trade accounts receivable $ 157,601 $ 137,696 Construction contract receivables 47,994 49,832 Retention receivables 15,010 14,973 Receivables from related parties 629 468 Accounts receivable 221,234 202,969 Less: Allowance for doubtful accounts (6,716 ) (4,639 ) Accounts receivable, net $ 214,518 $ 198,330
Summit Materials, LLC
Revenue from External Customer [Line Items]
Summary of Revenue by Products	Revenue by product for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 consisted of the following: 2018 2017 2016 Revenue by product*: Aggregates $ 373,824 $ 313,383 $ 264,609 Cement 258,876 282,041 250,349 Ready-mix concrete 584,114 492,302 395,917 Asphalt 301,247 285,653 239,419 Paving and related services 379,540 371,763 304,041 Other 203,401 187,433 171,728 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ *Revenue from the liquid asphalt terminals is included in asphalt revenue.
Summary of Contract Assets and Liabilities	The following table outlines the significant changes in contract assets and contract liability balances from December 30, 2017 to December 29, 2018 . Also included in the table is the net change in the estimate as a percentage of aggregate revenue for such contracts: Costs and estimated Billings in excess earnings in of costs and excess of billings estimated earnings Balance—December 30, 2017 $ 9,512 $ 15,750 Changes in revenue billed, contract price or cost estimates 8,702 (5,052 ) Acquisitions 483 1,179 Other (95 ) (37 ) Balance—December 29, 2018 $ 18,602 $ 11,840
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Trade accounts receivable $ 157,601 $ 137,696 Construction contract receivables 47,994 49,832 Retention receivables 15,010 14,973 Receivables from related parties 629 468 Accounts receivable 221,234 202,969 Less: Allowance for doubtful accounts (6,716 ) (4,639 ) Accounts receivable, net $ 214,518 $ 198,330

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 29, 2018
Inventory [Line Items]
Components of Inventories	Inventories consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Aggregate stockpiles $ 151,300 $ 126,791 Finished goods 34,993 34,667 Work in process 7,478 7,729 Raw materials 20,080 15,252 Total $ 213,851 $ 184,439
Summit Materials, LLC
Inventory [Line Items]
Components of Inventories	Inventories consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Aggregate stockpiles $ 151,300 $ 126,791 Finished goods 34,993 34,667 Work in process 7,478 7,729 Raw materials 20,080 15,252 Total $ 213,851 $ 184,439

Property, Plant and Equipment_2

Property, Plant and Equipment, net and Intangibles, net (Tables)	12 Months Ended
	Dec. 29, 2018
Property, Plant and Equipment [Line Items]
Summary of Property, Plant and Equipment	The estimated useful lives are generally as follows: Buildings and improvements 10 - 30 years Plant, machinery and equipment 15 - 20 years Office equipment 3 - 7 years Truck and auto fleet 5 - 8 years Mobile equipment and barges 6 - 8 years Landfill airspace and improvements 10 - 30 years Other 4 - 20 years Property, plant and equipment, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Land (mineral bearing) and asset retirement costs $ 323,553 $ 274,083 Land (non-mineral bearing) 184,029 168,501 Buildings and improvements 173,559 170,615 Plants, machinery and equipment 1,239,793 1,068,007 Mobile equipment and barges 468,313 391,256 Truck and auto fleet 51,938 47,270 Landfill airspace and improvements 49,754 49,480 Office equipment 39,794 33,314 Construction in progress 43,650 44,739 Property, plant and equipment 2,574,383 2,247,265 Less accumulated depreciation, depletion and amortization (794,251 ) (631,841 ) Property, plant and equipment, net $ 1,780,132 $ 1,615,424
Intangible Assets by Type and in Total	The following table shows intangible assets by type and in total: December 29, 2018 December 30, 2017 Gross Net Gross Net Carrying Accumulated Carrying Carrying Accumulated Carrying Amount Amortization Amount Amount Amortization Amount Leases $ 19,064 $ (5,259 ) $ 13,805 $ 15,888 $ (4,178 ) $ 11,710 Reserve rights 6,234 (1,940 ) 4,294 6,234 (1,625 ) 4,609 Trade names 1,000 (858 ) 142 1,000 (758 ) 242 Other 409 (190 ) 219 409 (137 ) 272 Total intangible assets $ 26,707 $ (8,247 ) $ 18,460 $ 23,531 $ (6,698 ) $ 16,833
Estimated Amortization Expense for Intangible Assets	The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows: 2019 $ 1,588 2020 1,510 2021 1,475 2022 1,482 2023 1,349 Thereafter 11,056 Total $ 18,460
Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Summary of Property, Plant and Equipment	Property, plant and equipment, net consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Land (mineral bearing) and asset retirement costs $ 323,553 $ 274,083 Land (non-mineral bearing) 184,029 168,501 Buildings and improvements 173,559 170,615 Plants, machinery and equipment 1,239,793 1,068,007 Mobile equipment and barges 468,313 391,256 Truck and auto fleet 51,938 47,270 Landfill airspace and improvements 49,754 49,480 Office equipment 39,794 33,314 Construction in progress 43,650 44,739 Property, plant and equipment 2,574,383 2,247,265 Less accumulated depreciation, depletion and amortization (794,251 ) (631,841 ) Property, plant and equipment, net $ 1,780,132 $ 1,615,424 The estimated useful lives are generally as follows: Buildings and improvements 10-30 years Plant, machinery and equipment 15 - 20 years Office equipment 3-7 years Truck and auto fleet 5-8 years Mobile equipment and barges 6-8 years Landfill airspace and improvements 10-30 years Other 4-20 years
Intangible Assets by Type and in Total	The intangible assets are amortized on a straight-line basis over the lives of the leases. The following table shows intangible assets by type and in total: December 29, 2018 December 30, 2017 Gross Net Gross Net Carrying Accumulated Carrying Carrying Accumulated Carrying Amount Amortization Amount Amount Amortization Amount Leases $ 19,064 $ (5,259 ) $ 13,805 $ 15,888 $ (4,178 ) $ 11,710 Reserve rights 6,234 (1,940 ) 4,294 6,234 (1,625 ) 4,609 Trade names 1,000 (858 ) 142 1,000 (758 ) 242 Other 409 (190 ) 219 409 (137 ) 272 Total intangible assets $ 26,707 $ (8,247 ) $ 18,460 $ 23,531 $ (6,698 ) $ 16,833
Estimated Amortization Expense for Intangible Assets	The estimated amortization expense for intangible assets for each of the next five years and thereafter is as follows: 2019 $ 1,588 2020 1,510 2021 1,475 2022 1,482 2023 1,349 Thereafter 11,056 Total $ 18,460

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 29, 2018
Schedule Of Accrued Expenses [Line Items]
Components of Accrued Expenses	Accrued expenses consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Interest $ 26,223 $ 24,095 Payroll and benefits 15,952 33,915 Capital lease obligations 15,557 19,276 Insurance 13,625 11,455 Non-income taxes 7,442 7,236 Professional fees 1,408 1,717 Other (1) 20,284 18,935 Total $ 100,491 $ 116,629 ______________________ (1) Consists primarily of subcontractor and working capital settlement accruals and deferred revenue.
Summit Materials, LLC
Schedule Of Accrued Expenses [Line Items]
Components of Accrued Expenses	Accrued expenses consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Interest $ 26,223 $ 24,095 Payroll and benefits 15,952 33,915 Capital lease obligations 15,557 19,276 Insurance 13,625 11,455 Non-income taxes 7,674 7,467 Professional fees 1,408 1,717 Other (1) 19,590 18,349 Total $ 100,029 $ 116,274 ______________________ (1) Consists primarily of subcontractor and working capital settlement accruals and deferred revenue.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 29, 2018
Schedule of Debt	Debt consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Term Loan, due 2024: $630.6 million and $635.4 million, net of $1.3 million and $1.6 million discount at December 29, 2018 and December 30, 2017, respectively $ 629,268 $ 633,805 8 1/2% Senior Notes, due 2022 250,000 250,000 6 1/8% Senior Notes, due 2023: $650.0 million, net of $1.1 million and $1.4 million discount at December 29, 2018 and December 30, 2017, respectively 648,891 648,650 5 1/8% Senior Notes, due 2025 300,000 300,000 Total 1,828,159 1,832,455 Current portion of long-term debt 6,354 4,765 Long-term debt $ 1,821,805 $ 1,827,690
Schedule of Contractual Payments of Long-Term Debt	The contractual payments of long-term debt, including current maturities, for the five years subsequent to December 29, 2018 , are as follows: 2019 $ 6,354 2020 7,942 2021 6,354 2022 256,354 2023 656,354 Thereafter 897,253 Total 1,830,611 Less: Original issue net discount (2,452 ) Less: Capitalized loan costs (14,303 ) Total debt $ 1,813,856
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the years ended December 29, 2018 and December 30, 2017 : Deferred financing fees Balance—December 31, 2016 $ 18,290 Loan origination fees 6,416 Amortization (3,990 ) Write off of deferred financing fees (1,683 ) Balance—December 30, 2017 $ 19,033 Loan origination fees 550 Amortization (4,108 ) Balance—December 29, 2018 $ 15,475
Summit Materials, LLC
Schedule of Debt	Debt consisted of the following as of December 29, 2018 and December 30, 2017 : 2018 2017 Term Loan, due 2024: $630.6 million and $635.4 million, net of $1.3 million and $1.6 million discount at December 29, 2018 and December 30, 2017, respectively $ 629,268 $ 633,805 8 1/2% Senior Notes, due 2022 250,000 250,000 6 1/8% Senior Notes, due 2023: $650.0 million, net of $1.1 million and $1.4 million discount at December 29, 2018 and December 30, 2017, respectively 648,891 648,650 5 1/8% Senior Notes, due 2025 300,000 300,000 Total 1,828,159 1,832,455 Current portion of long-term debt 6,354 4,765 Long-term debt $ 1,821,805 $ 1,827,690
Schedule of Contractual Payments of Long-Term Debt	The contractual payments of long-term debt, including current maturities, for the five years subsequent to December 29, 2018 , are as follows: 2019 $ 6,354 2020 7,942 2021 6,354 2022 256,354 2023 656,354 Thereafter 897,253 Total 1,830,611 Less: Original issue net discount (2,452 ) Less: Capitalized loan costs (14,303 ) Total debt $ 1,813,856
Summary of Activity for Deferred Financing Fees	The following table presents the activity for the deferred financing fees for the years ended December 29, 2018 and December 30, 2017 : Deferred financing fees Balance—December 31, 2016 $ 18,290 Loan origination fees 6,416 Amortization (3,990 ) Write off of deferred financing fees (1,683 ) Balance—December 30, 2017 $ 19,033 Loan origination fees 550 Amortization (4,108 ) Balance—December 29, 2018 $ 15,475

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 29, 2018
Income Taxes [Line Items]
Components of Income Tax Benefit	For the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , income taxes consisted of the following: 2018 2017 2016 Provision for income taxes: Current $ 463 $ 2,530 $ 2,835 Deferred 59,284 (286,507 ) (8,134 ) Income tax expense (benefit) $ 59,747 $ (283,977 ) $ (5,299 )
Schedule of Reconciliation of Income Tax (Benefit) Expense	The effective tax rate on pre-tax income differs from the U.S. statutory rate of 21% , 35% , and 35% for 2018 , 2017 and 2016 , respectively, due to the following: 2018 2017 2016 Income tax expense (benefit) at federal statutory tax rate $ 20,177 $ (55,365 ) $ 14,290 Less: Income tax benefit at federal statutory tax rate for LLC entities (561 ) (2,123 ) (10,608 ) State and local income taxes 4,894 (5,209 ) 2,490 Permanent differences (5,537 ) (4,410 ) (5,902 ) Effective tax rate change 4,034 216,904 (1,432 ) Unrecognized tax benefits 22,663 — — Tax receivable agreement (benefit) expense (8,282 ) 104,804 5,228 Change in valuation allowance 17,592 (500,162 ) 239,008 Impact of LP Unit ownership change — (31,790 ) (252,456 ) Other 4,767 (6,626 ) 4,083 Income tax expense (benefit) $ 59,747 $ (283,977 ) $ (5,299 )
Components of Net Deferred Income Tax Liability	The following table summarizes the components of the net deferred income tax asset (liability) as December 29, 2018 and December 30, 2017 : 2018 2017 Deferred tax assets (liabilities): Net intangible assets $ 275,412 $ 316,950 Accelerated depreciation (185,020 ) (147,943 ) Net operating loss 143,234 94,751 Investment in limited partnership (29,981 ) (14,467 ) Mining reclamation reserve 1,600 1,239 Inventory purchase accounting adjustments — — Working capital (e.g., accrued compensation, prepaid assets) 36,932 35,237 Interest expense limitation carryforward 2,586 — Less valuation allowance (19,366 ) (1,675 ) Deferred tax assets 225,397 284,092 Less foreign deferred tax liability (included in other noncurrent liabilities) (5,133 ) (3,992 ) Net deferred tax asset $ 220,264 $ 280,100
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: Unrealized Tax Benefits Balance—December 30, 2017 $ — Additions based on tax position in 2018 22,663 Balance—December 29, 2018 $ 22,663
Summary of Valuation Allowance	2018 2017 Valuation Allowance: Beginning balance $ (1,675 ) $ (502,839 ) Additional basis from exchanged LP Units (99 ) (31,790 ) Current year increases from operations (17,592 ) — Release of valuation allowance and other — 532,954 Ending balance $ (19,366 ) $ (1,675 )
Summit Materials, LLC
Income Taxes [Line Items]
Components of Income Tax Benefit	For the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 , income taxes consisted of the following: 2018 2017 2016 Provision for income taxes: Current $ 463 $ 2,762 $ 2,835 Deferred 9,810 (23,107 ) (8,117 ) Income tax benefit $ 10,273 $ (20,345 ) $ (5,282 )
Schedule of Reconciliation of Income Tax (Benefit) Expense	The effective tax rate on pre-tax income differs from the U.S. statutory rate of 21% , 35% and 35% for 2018, 2017 and 2016, respectively, due to the following: 2018 2017 2016 Income tax expense (benefit) at federal statutory tax rate $ 15,563 $ 39,797 $ 19,882 Less: Income tax benefit at federal statutory tax rate for LLC entities (13,863 ) (36,171 ) (21,042 ) State and local income taxes 1,614 1,751 1,279 Permanent differences (1,194 ) (630 ) (1,726 ) Effective tax rate change (1,148 ) (24,243 ) (1,432 ) Unrecognized tax benefits 6,487 — — Valuation allowance 2,586 — 148 Other 228 (849 ) (2,391 ) Income tax benefit $ 10,273 $ (20,345 ) $ (5,282 )
Components of Net Deferred Income Tax Liability	The following table summarizes the components of the net deferred income tax asset (liability) as December 29, 2018 and December 30, 2017 : 2018 2017 Deferred tax (liabilities) assets: Accelerated depreciation $ (57,437 ) $ (47,920 ) Net operating loss 22,915 20,671 Investment in limited partnership (16,591 ) (10,800 ) Net intangible assets (1,734 ) (1,256 ) Mining reclamation reserve 570 488 Working capital (e.g., accrued compensation, prepaid assets) 1,059 1,267 Interest expense limitation carryforward 2,586 — Net deferred tax liabilities (48,632 ) (37,550 ) Less valuation allowance (4,261 ) (1,675 ) Net deferred tax liability $ (52,893 ) $ (39,225 )
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: Unrealized Tax Benefits Balance—December 30, 2017 $ — Additions based on tax position in 2018 6,487 Balance—December 29, 2018 $ 6,487

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 29, 2018
Earnings Per Share [Abstract]
Schedule of Basic Earnings Per Share	The following table shows the calculation of basic income per share: 2018 2017 2016 Net income attributable to Summit Inc. $ 33,906 $ 121,830 $ 36,783 Weighted average shares of Class A stock outstanding 111,380,175 108,696,438 70,355,042 Basic income per share $ 0.30 $ 1.12 $ 0.52 Net income (loss) attributable to Summit Inc. $ 33,906 $ 121,830 $ 36,783 Weighted average shares of Class A stock outstanding 111,380,175 108,696,438 70,355,042 Add: weighted average of LP Units — — — Add: stock options 282,329 308,355 140,142 Add: warrants 25,049 42,035 16,123 Add: restricted stock units 459,280 308,221 240,633 Add: performance stock units 169,813 135,849 86,568 Weighted average dilutive shares outstanding 112,316,646 109,490,898 70,838,508 Diluted earnings per share $ 0.30 $ 1.11 $ 0.52
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Excluded from the above calculations were the shares noted below as they were antidilutive: 2018 2017 2016 Antidilutive shares: LP Units 3,512,669 4,371,705 32,327,907

Stockholder's Equity_Members'_2

Stockholder's Equity/Members' Interest (Tables)	12 Months Ended
	Dec. 29, 2018
Company Information
Schedule of Changes in Ownership of Summit Holdings	The following table summarizes the changes in our ownership of Summit Holdings: Summit Inc. Shares (Class A) LP Units Total Summit Inc. Ownership Percentage Balance — December 31, 2016 97,554,278 5,151,297 102,705,575 95.0 % January 2017 public offering 10,000,000 — 10,000,000 Exchanges during period 1,461,677 (1,461,677 ) — Other equity transactions 1,334,639 — 1,334,639 Balance — December 30, 2017 110,350,594 3,689,620 114,040,214 96.8 % Exchanges during period 254,102 (254,102 ) — Other equity transactions 1,054,231 — 1,054,231 Balance — December 29, 2018 111,658,927 3,435,518 115,094,445 97.0 %
Schedule of Changes in Each Component of Accumulated Other Comprehensive Income (Loss)	The changes in each component of accumulated other comprehensive income (loss) consisted of the following: Accumulated Foreign currency other Change in translation Cash flow hedge comprehensive retirement plans adjustments adjustments income (loss) Balance — December 31, 2016 $ 1,450 $ (3,106 ) $ (593 ) $ (2,249 ) Postretirement curtailment adjustment, net of tax 309 — — 309 Postretirement liability adjustment, net of tax 605 — — 605 Foreign currency translation adjustment, net of tax — 7,743 — 7,743 Income on cash flow hedges, net of tax — — 978 978 Balance — December 30, 2017 $ 2,364 $ 4,637 $ 385 $ 7,386 Postretirement liability adjustment, net of tax 1,209 — — 1,209 Foreign currency translation adjustment, net of tax — (6,784 ) — (6,784 ) Income on cash flow hedges, net of tax — — 870 870 Balance — December 29, 2018 $ 3,573 $ (2,147 ) $ 1,255 $ 2,681
Summit Materials, LLC
Company Information
Schedule of Changes in Each Component of Accumulated Other Comprehensive Income (Loss)	The changes in each component of accumulated other comprehensive income (loss) consisted of the following: Accumulated Foreign currency other Change in translation Cash flow hedge comprehensive retirement plans adjustments adjustments (loss) income Balance — December 31, 2016 $ (7,181 ) $ (17,790 ) $ (2,473 ) $ (27,444 ) Postretirement curtailment adjustment 429 — — 429 Postretirement liability adjustment 699 — — 699 Foreign currency translation adjustment — 7,768 — 7,768 Income on cash flow hedges — — 1,413 1,413 Balance — December 30, 2017 $ (6,053 ) $ (10,022 ) $ (1,060 ) $ (17,135 ) Postretirement liability adjustment 1,661 — — 1,661 Foreign currency translation adjustment — (9,348 ) — (9,348 ) Income on cash flow hedges — — 1,206 1,206 Balance — December 29, 2018 $ (4,392 ) $ (19,370 ) $ 146 $ (23,616 )

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 29, 2018
Schedule Of Cash Flow Supplemental [Line Items]
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was as follows: 2018 2017 2016 Cash payments: Interest $ 103,250 $ 96,320 $ 82,540 Income taxes 3,340 1,711 2,645 Non cash financing activities: Purchase of noncontrolling interest $ — $ (716 ) $ — Stock Dividend — (45,023 ) (26,939 ) Exchange of LP Units to shares of Class A common stock 7,499 41,126 953,752
Summit Materials, LLC
Schedule Of Cash Flow Supplemental [Line Items]
Schedule of Supplemental Cash Flow Information	Supplemental cash flow information for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 was as follows: 2018 2017 2016 Cash payments: Interest $ 103,250 $ 96,320 $ 82,540 Income taxes 3,340 1,711 2,645 Non cash financing activities: Purchase of noncontrolling interest $ — $ (716 ) $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 29, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Information for the Equity Awards Granted	The following table summarizes information for the equity awards granted in 2018: Options Restricted Stock Units Performance Stock Units Warrants Weighted Weighted Weighted Weighted average grant- Number of average grant- Number of average grant- average grant- Number of date fair value restricted date fair value performance date fair value Number of date fair value options per unit stock units per unit stock units per unit warrants per unit Beginning balance—December 30, 2017 4,153,613 $ 9.13 508,586 $ 20.14 211,455 $ 23.69 102,778 $ 18.00 Granted — — 689,386 28.68 102,842 40.83 — — Forfeited (22,566 ) 10.91 (21,551 ) 28.11 (19,045 ) 26.26 — — Exercised (863,898 ) 8.88 — — — — (2,741 ) 18.00 Vested — — (252,113 ) 21.95 — — — — Balance—December 29, 2018 3,267,149 $ 9.09 924,308 $ 24.57 295,252 $ 29.12 100,037 $ 18.00
Weighted Average Assumptions Used to Estimate the Fair Value of Grants	The following table presents the weighted average assumptions used to estimate the fair value of grants in 2018, 2017 and 2016: Options Performance Stock Units 2017 2016 2018 2017 2016 Risk-free interest rate 2.06% - 2.31% 1.75% - 1.97% 2.38% 1.45% 0.88% Dividend yield N/A N/A N/A N/A N/A Volatility 47% 48% 38% 39% 37% Expected term 7 years 10 years 3 years 3 years 3 years
Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Information for the Equity Awards Granted	The following table summarizes information for the equity awards granted in 2018: Options Restricted Stock Units Performance Stock Units Warrants Weighted Weighted Weighted Weighted average grant- Number of average grant- Number of average grant- average grant- Number of date fair value restricted date fair value performance date fair value Number of date fair value options per unit stock units per unit stock units per unit warrants per unit Beginning balance—December 30, 2017 4,153,613 $ 9.13 508,586 $ 20.14 211,455 $ 23.69 102,778 $ 18.00 Granted — — 689,386 28.68 102,842 40.83 — — Forfeited (22,566 ) 10.91 (21,551 ) 28.11 (19,045 ) 26.26 — — Exercised (863,898 ) 8.88 — — — — (2,741 ) 18.00 Vested — — (252,113 ) 21.95 — — — — Balance—December 29, 2018 3,267,149 $ 9.09 924,308 $ 24.57 295,252 $ 29.12 100,037 $ 18.00
Weighted Average Assumptions Used to Estimate the Fair Value of Grants	The following table presents the weighted average assumptions used to estimate the fair value of grants in 2018, 2017 and 2016: Options Performance Stock Units 2017 2016 2018 2017 2016 Risk-free interest rate 2.06% - 2.31% 1.75% - 1.97% 2.38% 1.45% 0.88% Dividend yield N/A N/A N/A N/A N/A Volatility 47% 48% 38% 39% 37% Expected term 7 years 10 years 3 years 3 years 3 years

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Obligations and Funded Status	The following information is as of December 29, 2018 and December 30, 2017 and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. Change in benefit obligations: Beginning of period $ 27,984 $ 9,793 $ 27,608 $ 12,770 Service cost 67 170 285 184 Interest cost 898 317 998 365 Actuarial (gain) loss (3,136 ) (173 ) 1,182 (338 ) Curtailments — — (430 ) — Change in plan provision — — — (2,325 ) Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 24,203 $ 9,203 $ 27,984 $ 9,793 Change in fair value of plan assets: Beginning of period $ 19,012 $ — $ 18,395 $ — Actual return on plan assets (551 ) — 1,415 — Employer contributions 598 904 861 863 Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 17,449 $ — $ 19,012 $ — Funded status of plans $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Current liabilities $ — $ — $ — $ (702 ) Noncurrent liabilities (6,754 ) (9,203 ) (8,972 ) (9,091 ) Liability recognized $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Amounts recognized in accumulated other comprehensive income: Net actuarial (gain) loss $ (1,300 ) $ 1,995 $ 9,341 $ 2,285 Prior service cost (312 ) (2,172 ) — (2,413 ) Total amount recognized $ (1,612 ) $ (177 ) $ 9,341 $ (128 )
Amounts Recognized in Other Comprehensive (Gain) Loss	2018 2017 2016 Pension Healthcare Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. benefits & Life Ins. Amounts recognized in other comprehensive (income) loss: Net actuarial (loss) gain $ (1,300 ) $ (172 ) $ 1,068 $ (338 ) $ 688 $ (682 ) Prior service cost — — — (572 ) — 64 Amortization of prior year service cost — 241 — 168 — 174 Curtailment benefit — — (429 ) — — — Amortization of gain (312 ) (118 ) (547 ) (64 ) (463 ) (207 ) Adjustment to plan benefits — — — (414 ) — — Total amount recognized $ (1,612 ) $ (49 ) $ 92 $ (1,220 ) $ 225 $ (651 )
Schedule of Net Benefit Costs	Components of net periodic benefit cost: Service cost $ 67 $ 170 $ 285 $ 184 $ 279 $ 230 Interest cost 898 317 998 365 1,049 470 Amortization of gain 312 118 547 64 463 207 Expected return on plan assets (1,284 ) — (1,302 ) — (1,386 ) — Curtailments — — — — — — Amortization of prior service credit — (241 ) — (168 ) — (174 ) Net periodic (expense) benefit cost $ (7 ) $ 364 $ 528 $ 445 $ 405 $ 733
Schedule of Assumptions Used	Weighted-average assumptions used to determine the benefit obligations as of year-end 2018 and 2017 are: 2018 2017 Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.90% - 4.02% 3.87% - 3.91% 3.23% - 3.37% 3.20% - 3.25% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A Weighted-average assumptions used to determine net periodic benefit cost for years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Healthcare Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.23% - 3.37% 3.20% - 3.25% 3.61% - 3.81% 3.54% - 3.65% 3.74% - 3.97% 3.34% - 3.80% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A 7.30% N/A
Effects of One Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one percentage-point change in assumed health care cost trend rates would have the following effects as of year-end 2018 and 2017 : 2018 2017 Increase Decrease Increase Decrease Total service cost and interest cost components $ 31 $ (27 ) $ 39 $ (33 ) APBO 765 (690 ) 857 (769 )
Fair Value of Company's Pension Plans' Assets	The fair value of the Plans’ assets by asset class and fair value hierarchy level as of December 29, 2018 and December 30, 2017 are as follows: 2018 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,547 $ 3,547 $ — Intermediate—corporate 3,437 — 3,437 Short-term—government 756 756 — Short-term—corporate 957 — 957 International 1,143 — 1,143 Equity securities: U.S. Large cap value 978 978 — U.S. Large cap growth 976 976 — U.S. Mid cap value 471 471 — U.S. Mid cap growth 496 496 — U.S. Small cap value 463 463 — U.S. Small cap growth 474 474 — Managed Futures 355 — 355 International 1,004 329 675 Emerging Markets 362 362 — Commodities Broad Basket 1,048 388 660 Cash 982 982 — Total $ 17,449 $ 10,222 $ 7,227 2017 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,620 $ 3,068 $ 552 Intermediate—corporate 3,872 — 3,872 Short-term—government 497 497 — Short-term—corporate 1,702 — 1,702 Equity securities: U.S. Large cap value 1,765 1,765 — U.S. Large cap growth 588 588 — U.S. Mid cap value 586 586 — U.S. Mid cap growth 586 586 — U.S. Small cap value 571 571 — U.S. Small cap growth 580 580 — Managed Futures 392 — 392 International 1,547 677 870 Commodities Broad Basket 801 — 801 Cash 1,522 — 1,522 Precious metals 383 383 — Total $ 19,012 $ 9,301 $ 9,711
Estimated Benefit Payments	The estimated benefit payments for each of the next five years and the five-year period thereafter are as follows: Pension Healthcare and Life benefits Insurance Benefits 2019 $ 1,736 $ 687 2020 1,712 697 2021 1,680 681 2022 1,678 669 2023 1,676 664 2024 - 2028 7,806 3,415
Schedule of Multiemployer Plans	Expiration Date of Pension Protection Act FIP/RP Status Contributions of Company Collective- Pension EIN/ Pension Zone Status Pending/ ($ in thousands) Surcharge Bargaining Trust Fund Plan Number 2018 2017 Implemented 2018 2017 Imposed Agreement (1) Construction Industry Laborers Pension Fund 43-6060737/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None $ 115 $ 104 No 12/31/2018 Operating Engineers Local 101 Pension Plan 43-6059213/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None 26 30 No 12/31/2018 Total Contributions $ 141 $ 134 _____________________ (1) C urrently in final negotiations to extend both collective-bargaining agreements.
Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Obligations and Funded Status	The following information is as of December 29, 2018 and December 30, 2017 and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. Change in benefit obligations: Beginning of period $ 27,984 $ 9,793 $ 27,608 $ 12,770 Service cost 67 170 285 184 Interest cost 898 317 998 365 Actuarial (gain) loss (3,136 ) (173 ) 1,182 (338 ) Curtailments — — (430 ) — Change in plan provision — — — (2,325 ) Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 24,203 $ 9,203 $ 27,984 $ 9,793 Change in fair value of plan assets: Beginning of period $ 19,012 $ — $ 18,395 $ — Actual return on plan assets (551 ) — 1,415 — Employer contributions 598 904 861 863 Benefits paid (1,610 ) (904 ) (1,659 ) (863 ) End of period $ 17,449 $ — $ 19,012 $ — Funded status of plans $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Current liabilities $ — $ — $ — $ (702 ) Noncurrent liabilities (6,754 ) (9,203 ) (8,972 ) (9,091 ) Liability recognized $ (6,754 ) $ (9,203 ) $ (8,972 ) $ (9,793 ) Amounts recognized in accumulated other comprehensive income: Net actuarial (gain) loss $ (1,300 ) $ 1,995 $ 9,341 $ 2,285 Prior service cost (312 ) (2,172 ) — (2,413 ) Total amount recognized $ (1,612 ) $ (177 ) $ 9,341 $ (128 )
Amounts Recognized in Other Comprehensive (Gain) Loss	2018 2017 2016 Pension Healthcare Pension Healthcare Pension Healthcare benefits & Life Ins. benefits & Life Ins. benefits & Life Ins. Amounts recognized in other comprehensive (income) loss: Net actuarial (loss) gain $ (1,300 ) $ (172 ) $ 1,068 $ (338 ) $ 688 $ (682 ) Prior service cost — — — (572 ) — 64 Amortization of prior year service cost — 241 — 168 — 174 Curtailment benefit — — (429 ) — — — Amortization of gain (312 ) (118 ) (547 ) (64 ) (463 ) (207 ) Adjustment to plan benefits — — — (414 ) — — Total amount recognized $ (1,612 ) $ (49 ) $ 92 $ (1,220 ) $ 225 $ (651 ) Components of net periodic benefit cost: Service cost $ 67 $ 170 $ 285 $ 184 $ 279 $ 230 Interest cost 898 317 998 365 1,049 470 Amortization of gain 312 118 547 64 463 207 Expected return on plan assets (1,284 ) — (1,302 ) — (1,386 ) — Curtailments — — — — — — Amortization of prior service credit — (241 ) — (168 ) — (174 ) Net periodic (expense) benefit cost $ (7 ) $ 364 $ 528 $ 445 $ 405 $ 733
Schedule of Assumptions Used	Weighted-average assumptions used to determine the benefit obligations as of year-end 2018 and 2017 are: 2018 2017 Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.90% - 4.02% 3.87% - 3.91% 3.23% - 3.37% 3.20% - 3.25% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A Weighted-average assumptions used to determine net periodic benefit cost for years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Healthcare Healthcare Healthcare Pension benefits & Life Ins. Pension benefits & Life Ins. Pension benefits & Life Ins. Discount rate 3.23% - 3.37% 3.20% - 3.25% 3.61% - 3.81% 3.54% - 3.65% 3.74% - 3.97% 3.34% - 3.80% Expected long-term rate of return on plan assets 7.00% N/A 7.00% N/A 7.30% N/A
Effects of One Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one percentage-point change in assumed health care cost trend rates would have the following effects as of year-end 2018 and 2017 : 2018 2017 Increase Decrease Increase Decrease Total service cost and interest cost components $ 31 $ (27 ) $ 39 $ (33 ) APBO 765 (690 ) 857 (769 )
Fair Value of Company's Pension Plans' Assets	The fair value of the Plans’ assets by asset class and fair value hierarchy level as of December 29, 2018 and December 30, 2017 are as follows: 2018 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,547 $ 3,547 $ — Intermediate—corporate 3,437 — 3,437 Short-term—government 756 756 — Short-term—corporate 957 — 957 International 1,143 — 1,143 Equity securities: U.S. Large cap value 978 978 — U.S. Large cap growth 976 976 — U.S. Mid cap value 471 471 — U.S. Mid cap growth 496 496 — U.S. Small cap value 463 463 — U.S. Small cap growth 474 474 — Managed Futures 355 — 355 International 1,004 329 675 Emerging Markets 362 362 — Commodities Broad Basket 1,048 388 660 Cash 982 982 — Total $ 17,449 $ 10,222 $ 7,227 2017 Quoted prices in active Total fair markets for identical Observable value assets (Level 1) inputs (Level 2) Fixed income securities: Intermediate—government $ 3,620 $ 3,068 $ 552 Intermediate—corporate 3,872 — 3,872 Short-term—government 497 497 — Short-term—corporate 1,702 — 1,702 Equity securities: U.S. Large cap value 1,765 1,765 — U.S. Large cap growth 588 588 — U.S. Mid cap value 586 586 — U.S. Mid cap growth 586 586 — U.S. Small cap value 571 571 — U.S. Small cap growth 580 580 — Managed Futures 392 — 392 International 1,547 677 870 Commodities Broad Basket 801 — 801 Cash 1,522 — 1,522 Precious metals 383 383 — Total $ 19,012 $ 9,301 $ 9,711
Estimated Benefit Payments	The estimated benefit payments for each of the next five years and the five-year period thereafter are as follows: Pension Healthcare and Life benefits Insurance Benefits 2019 $ 1,736 $ 687 2020 1,712 697 2021 1,680 681 2022 1,678 669 2023 1,676 664 2024 - 2028 7,806 3,415
Schedule of Multiemployer Plans	Expiration Date of Pension Protection Act FIP/RP Status Contributions of Company Collective- Pension EIN/ Pension Zone Status Pending/ ($ in thousands) Surcharge Bargaining Trust Fund Plan Number 2018 2017 Implemented 2018 2017 Imposed Agreement (1) Construction Industry Laborers Pension Fund 43-6060737/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None $ 115 $ 104 No 12/31/2018 Operating Engineers Local 101 Pension Plan 43-6059213/001 Green - as of December 31, 2017 Green - as of December 31, 2016 None 26 30 No 12/31/2018 Total Contributions $ 141 $ 134 ______________________ (1) Currently in final negotiations to extend both collective-bargaining agreements.

Accrued Mining and Landfill R_2

Accrued Mining and Landfill Reclamation (Tables)	12 Months Ended
	Dec. 29, 2018
Asset Retirement Obligations [Line Items]
Activity for Asset Retirement Obligations	The following table presents the activity for the asset retirement obligations for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 Beginning balance $ 24,329 $ 23,906 Acquired obligations 3,937 2,303 Change in cost estimate 2,808 (1,759 ) Settlement of reclamation obligations (1,680 ) (1,996 ) Accretion expense 1,605 1,875 Ending balance $ 30,999 $ 24,329
Summit Materials, LLC
Asset Retirement Obligations [Line Items]
Activity for Asset Retirement Obligations	The following table presents the activity for the asset retirement obligations for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 Beginning balance $ 24,329 $ 23,906 Acquired obligations 3,937 2,303 Change in cost estimate 2,808 (1,759 ) Settlement of reclamation obligations (1,680 ) (1,996 ) Accretion expense 1,605 1,875 Ending balance $ 30,999 $ 24,329

Leasing Arrangements (Tables)

Leasing Arrangements (Tables)	12 Months Ended
	Dec. 29, 2018
Lease Rental Expenses [Line Items]
Minimum Contractual Commitments for the Subsequent Five Years under Long-Term Operating Leases	Minimum contractual commitments for the subsequent five years under long-term operating leases and under royalty agreements are as follows: Operating Royalty Leases Agreements 2019 $ 9,479 $ 7,124 2020 8,101 6,929 2021 6,701 6,665 2022 4,279 6,742 2023 3,411 6,656
Summit Materials, LLC
Lease Rental Expenses [Line Items]
Minimum Contractual Commitments for the Subsequent Five Years under Long-Term Operating Leases	Minimum contractual commitments for the subsequent five years under long-term operating leases and under royalty agreements are as follows: Operating Royalty Leases Agreements 2019 $ 9,479 $ 7,124 2020 8,101 6,929 2021 6,701 6,665 2022 4,279 6,742 2023 3,411 6,656

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 29, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Schedule of Contingent Consideration and Derivatives Measured at Fair Value	he fair value of contingent consideration and derivatives as of December 29, 2018 and December 30, 2017 was: 2018 2017 Current portion of acquisition-related liabilities and Accrued expenses: Contingent consideration $ 1,394 $ 594 Cash flow hedges — 488 Acquisition-related liabilities and Other noncurrent liabilities Contingent consideration $ 5,175 $ 34,301 Cash flow hedges — 492
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of December 29, 2018 and December 30, 2017 were: December 29, 2018 December 30, 2017 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt(1) $ 1,777,722 $ 1,828,159 $ 1,893,239 $ 1,832,455 Level 3 Current portion of deferred consideration and noncompete obligations(2) 32,876 32,876 13,493 13,493 Long term portion of deferred consideration and noncompete obligations(3) 44,293 44,293 23,834 23,834 _____________________ (1) $6.4 million and $4.8 million included in current portion of debt as of December 29, 2018 and December 30, 2017 , respectively. (2) Included in current portion of acquisition-related liabilities on the consolidated balance sheets. (3) Included in acquisition-related liabilities on the consolidated balance sheets.
Summit Materials, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Schedule of Contingent Consideration and Derivatives Measured at Fair Value	The fair value of contingent consideration and derivatives as of December 29, 2018 and December 30, 2017 was: 2018 2017 Current portion of acquisition-related liabilities and Accrued expenses: Contingent consideration $ 1,394 $ 594 Cash flow hedges — 488 Acquisition-related liabilities and Other noncurrent liabilities Contingent consideration $ 5,175 $ 34,301 Cash flow hedges — 492
Schedule of Carrying Value and Fair Value of Financial Instruments	The carrying value and fair value of these financial instruments as of December 29, 2018 and December 30, 2017 were: December 29, 2018 December 30, 2017 Fair Value Carrying Value Fair Value Carrying Value Level 2 Long-term debt(1) $ 1,777,722 $ 1,828,159 $ 1,893,239 $ 1,832,455 Level 3 Current portion of deferred consideration and noncompete obligations(2) 30,376 30,376 10,993 10,993 Long term portion of deferred consideration and noncompete obligations(3) 40,179 40,179 17,938 17,938 ______________________ (1) $6.4 million and $4.8 million included in current portion of debt as of December 29, 2018 and December 30, 2017 , respectively. (2) Included in current portion of acquisition-related liabilities on the consolidated balance sheets. (3) Included in acquisition-related liabilities on the consolidated balance sheets.

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 29, 2018
Segment Reporting Information [Line Items]
Summary of Financial Data for Company's Reportable Business Segments	The following tables display selected financial data for the Company’s reportable business segments as of and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Revenue*: West $ 1,117,066 $ 998,843 $ 813,682 East 703,147 629,919 531,294 Cement 280,789 303,813 281,087 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Intercompany sales are immaterial and the presentation above only reflects sales to external customers. 2018 2017 2016 Income (loss) from operations before taxes $ 96,077 $ (158,200 ) $ 40,827 Interest expense 116,548 108,549 97,536 Depreciation, depletion and amortization 203,305 177,643 147,736 Accretion 1,605 1,875 1,564 IPO/ Legacy equity modification costs — — 37,257 Loss on debt financings 149 4,815 — Tax receivable agreement (benefit) expense (22,684 ) 271,016 14,938 Gain on sale of business (12,108 ) — — Transaction costs 4,238 7,733 6,797 Management fees and expenses — — (1,379 ) Non-cash compensation 25,378 21,140 12,683 Other (6,247 ) 1,206 13,388 Total Adjusted EBITDA $ 406,261 $ 435,777 $ 371,347 Total Adjusted EBITDA by Segment: West $ 188,999 $ 203,590 $ 167,434 East 138,032 139,108 126,007 Cement 111,394 127,547 112,991 Corporate and other (32,164 ) (34,468 ) (35,085 ) Total Adjusted EBITDA $ 406,261 $ 435,777 $ 371,347 2018 2017 2016 Purchases of property, plant and equipment West $ 120,657 $ 83,591 $ 77,335 East 64,384 68,556 45,492 Cement 28,036 35,803 25,408 Total reportable segments 213,077 187,950 148,235 Corporate and other 7,608 6,196 5,248 Total purchases of property, plant and equipment $ 220,685 $ 194,146 $ 153,483 2018 2017 2016 Depreciation, depletion, amortization and accretion: West $ 91,794 $ 71,314 $ 65,345 East 75,433 67,252 51,540 Cement 35,061 38,351 30,006 Total reportable segments 202,288 176,917 146,891 Corporate and other 2,622 2,601 2,409 Total depreciation, depletion, amortization and accretion $ 204,910 $ 179,518 $ 149,300 2018 2017 2016 Total assets: West $ 1,370,501 $ 1,225,463 $ 902,763 East 1,253,640 1,035,609 870,613 Cement 877,586 870,652 868,440 Total reportable segments 3,501,727 3,131,724 2,641,816 Corporate and other 355,914 655,609 139,650 Total $ 3,857,641 $ 3,787,333 $ 2,781,466
Summit Materials, LLC
Segment Reporting Information [Line Items]
Summary of Financial Data for Company's Reportable Business Segments	The following tables display selected financial data for the Company’s reportable business segments as of and for the years ended December 29, 2018 , December 30, 2017 and December 31, 2016 : 2018 2017 2016 Revenue*: West $ 1,117,066 $ 998,843 $ 813,682 East 703,147 629,919 531,294 Cement 280,789 303,813 281,087 Total revenue $ 2,101,002 $ 1,932,575 $ 1,626,063 ______________________ * Intercompany sales are immaterial and the presentation above only reflects sales to external customers. 2018 2017 2016 Income from operations before taxes $ 74,110 $ 113,696 $ 56,805 Interest expense 115,831 107,655 96,483 Depreciation, depletion and amortization 203,305 177,643 147,736 Accretion 1,605 1,875 1,564 IPO/ Legacy equity modification costs — — 37,257 Loss on debt financings 149 4,815 — Gain on sale of business (12,108 ) — — Transaction costs 4,238 7,733 6,797 Management fees and expenses — — (1,379 ) Non-cash compensation 25,378 21,140 12,683 Other (6,247 ) 1,206 13,388 Total Adjusted EBITDA $ 406,261 $ 435,763 $ 371,334 Total Adjusted EBITDA by Segment: West $ 188,999 $ 203,590 $ 167,434 East 138,032 139,108 126,007 Cement 111,394 127,547 112,991 Corporate and other (32,164 ) (34,482 ) (35,098 ) Total Adjusted EBITDA $ 406,261 $ 435,763 $ 371,334 2018 2017 2016 Purchases of property, plant and equipment West $ 120,657 $ 83,591 $ 77,335 East 64,384 68,556 45,492 Cement 28,036 35,803 25,408 Total reportable segments 213,077 187,950 148,235 Corporate and other 7,608 6,196 5,248 Total purchases of property, plant and equipment $ 220,685 $ 194,146 $ 153,483 2018 2017 2016 Depreciation, depletion, amortization and accretion: West $ 91,794 $ 71,314 $ 65,345 East 75,433 67,252 51,540 Cement 35,061 38,351 30,006 Total reportable segments 202,288 176,917 146,891 Corporate and other 2,622 2,601 2,409 Total depreciation, depletion, amortization and accretion $ 204,910 $ 179,518 $ 149,300 2018 2017 2016 Total assets: West $ 1,370,501 $ 1,225,463 $ 902,763 East 1,253,640 1,035,609 870,613 Cement 877,586 870,652 868,440 Total reportable segments 3,501,727 3,131,724 2,641,816 Corporate and other 131,517 372,517 134,604 Total $ 3,633,244 $ 3,504,241 $ 2,776,420

Senior Notes' Guarantor and N_2

Senior Notes' Guarantor and Non-Guarantor Financial Information (Tables) - Summit Materials, LLC	12 Months Ended
	Dec. 29, 2018
Condensed Financial Statements, Captions [Line Items]
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 117,219 $ 8,440 $ 7,719 $ (4,870 ) $ 128,508 Accounts receivable, net — 199,538 15,165 (185 ) 214,518 Intercompany receivables 500,765 624,427 — (1,125,192 ) — Cost and estimated earnings in excess of billings — 17,711 891 — 18,602 Inventories — 210,149 3,702 — 213,851 Other current assets 1,953 11,308 2,800 — 16,061 Total current assets 619,937 1,071,573 30,277 (1,130,247 ) 591,540 Property, plant and equipment, net 13,300 1,709,083 57,749 — 1,780,132 Goodwill — 1,136,785 56,243 — 1,193,028 Intangible assets, net — 18,460 — — 18,460 Other assets 3,292,851 154,080 947 (3,397,794 ) 50,084 Total assets $ 3,926,088 $ 4,089,981 $ 145,216 $ (4,528,041 ) $ 3,633,244 Liabilities and Member’s Interest Current liabilities: Current portion of debt $ 6,354 $ — $ — $ — $ 6,354 Current portion of acquisition-related liabilities — 31,770 — — 31,770 Accounts payable 4,712 92,132 12,349 (185 ) 109,008 Accrued expenses 45,146 57,826 1,927 (4,870 ) 100,029 Intercompany payables 673,175 436,564 15,453 (1,125,192 ) — Billings in excess of costs and estimated earnings — 11,347 493 — 11,840 Total current liabilities 729,387 629,639 30,222 (1,130,247 ) 259,001 Long-term debt 1,807,502 — — — 1,807,502 Acquisition-related liabilities — 45,354 — — 45,354 Other noncurrent liabilities 3,768 226,137 77,368 (171,317 ) 135,956 Total liabilities 2,540,657 901,130 107,590 (1,301,564 ) 2,247,813 Total member's interest 1,385,431 3,188,851 37,626 (3,226,477 ) 1,385,431 Total liabilities and member’s interest $ 3,926,088 $ 4,089,981 $ 145,216 $ (4,528,041 ) $ 3,633,244 Condensed Consolidating Balance Sheets December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 370,741 $ 10,254 $ 14,933 $ (12,372 ) $ 383,556 Accounts receivable, net — 183,139 15,191 — 198,330 Intercompany receivables 573,301 484,747 — (1,058,048 ) — Cost and estimated earnings in excess of billings — 9,264 248 — 9,512 Inventories — 180,283 4,156 — 184,439 Other current assets 1,167 6,354 243 — 7,764 Total current assets 945,209 874,041 34,771 (1,070,420 ) 783,601 Property, plant and equipment, net 9,259 1,569,118 37,047 — 1,615,424 Goodwill — 976,206 61,114 — 1,037,320 Intangible assets, net — 16,833 — — 16,833 Other assets 2,890,674 162,711 1,271 (3,003,593 ) 51,063 Total assets $ 3,845,142 $ 3,598,909 $ 134,203 $ (4,074,013 ) $ 3,504,241 Liabilities and Member’s Interest Current liabilities: Current portion of debt $ 4,765 $ — $ — $ — $ 4,765 Current portion of acquisition-related liabilities — 11,587 — — 11,587 Accounts payable 3,976 89,912 6,749 — 100,637 Accrued expenses 47,047 79,372 2,227 (12,372 ) 116,274 Intercompany payables 684,057 369,918 4,073 (1,058,048 ) — Billings in excess of costs and estimated earnings — 15,349 401 — 15,750 Total current liabilities 739,845 566,138 13,450 (1,070,420 ) 249,013 Long-term debt 1,810,833 — — — 1,810,833 Acquisition-related liabilities — 52,239 — — 52,239 Other noncurrent liabilities 2,870 193,801 75,209 (171,318 ) 100,562 Total liabilities 2,553,548 812,178 88,659 (1,241,738 ) 2,212,647 Total member's interest 1,291,594 2,786,731 45,544 (2,832,275 ) 1,291,594 Total liabilities and member’s interest $ 3,845,142 $ 3,598,909 $ 134,203 $ (4,074,013 ) $ 3,504,241
Condensed Consolidating Statements of Operations and Comprehensive Loss	Condensed Consolidating Statements of Operations and Comprehensive Loss Year Ended December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 2,018,428 $ 88,658 $ (6,084 ) $ 2,101,002 Cost of revenue (excluding items shown separately below) — 1,416,222 65,641 (6,084 ) 1,475,779 General and administrative expenses 62,376 184,917 10,554 — 257,847 Depreciation, depletion, amortization and accretion 2,622 197,406 4,882 — 204,910 Operating (loss) income (64,998 ) 219,883 7,581 — 162,466 Other (income) loss, net (249,204 ) (14,643 ) 823 247,657 (15,367 ) Interest expense (income) 118,857 (7,818 ) 4,792 — 115,831 Gain on sale of business — (12,108 ) — — (12,108 ) Income from operations before taxes 65,349 254,452 1,966 (247,657 ) 74,110 Income tax expense 1,512 8,226 535 — 10,273 Net income attributable to member of Summit Materials, LLC $ 63,837 $ 246,226 $ 1,431 $ (247,657 ) $ 63,837 Comprehensive income attributable to member of Summit Materials, LLC $ 57,356 $ 243,359 $ 10,779 $ (254,138 ) $ 57,356 Condensed Consolidating Statements of Operations and Comprehensive Loss Year ended December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 1,854,434 $ 84,020 $ (5,879 ) $ 1,932,575 Cost of revenue (excluding items shown separately below) — 1,227,037 60,619 (5,879 ) 1,281,777 General and administrative expenses 63,954 178,023 8,426 — 250,403 Depreciation, depletion, amortization and accretion 2,601 172,738 4,179 — 179,518 Operating (loss) income (66,555 ) 276,636 10,796 — 220,877 Other income, net (307,876 ) (1,925 ) (533 ) 309,860 (474 ) Interest expense (income) 105,735 (2,415 ) 4,335 — 107,655 Income from operations before taxes 135,586 280,976 6,994 (309,860 ) 113,696 Income tax expense (benefit) 1,518 (23,774 ) 1,911 — (20,345 ) Net income 134,068 304,750 5,083 (309,860 ) 134,041 Net loss attributable to noncontrolling interest — — — (27 ) (27 ) Net income attributable to member of Summit Materials, LLC $ 134,068 $ 304,750 $ 5,083 $ (309,833 ) $ 134,068 Comprehensive income (loss) attributable to member of Summit Materials, LLC $ 144,377 $ 302,209 $ (2,685 ) $ (299,524 ) $ 144,377 Condensed Consolidating Statements of Operations and Comprehensive Loss Year ended December 31, 2016 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Revenue $ — $ 1,586,858 $ 47,064 $ (7,859 ) $ 1,626,063 Cost of revenue (excluding items shown separately below) — 1,047,120 32,531 (7,859 ) 1,071,792 General and administrative expenses 91,533 152,402 6,374 — 250,309 Depreciation, depletion, amortization and accretion 2,410 142,773 4,117 — 149,300 Operating (loss) income (93,943 ) 244,563 4,042 — 154,662 Other (income) loss, net (239,082 ) 1,908 (326 ) 238,874 1,374 Interest expense 83,068 9,956 3,459 — 96,483 Income from continuing operations before taxes 62,071 232,699 909 (238,874 ) 56,805 Income tax (benefit) expense — (5,551 ) 269 — (5,282 ) Net income 62,071 238,250 640 (238,874 ) 62,087 Net income attributable to noncontrolling interest — — — 16 16 Net income attributable to member of Summit Materials, LLC $ 62,071 $ 238,250 $ 640 $ (238,890 ) $ 62,071 Comprehensive income attributable to member of Summit Materials, LLC $ 63,093 $ 239,353 $ (1,485 ) $ (237,868 ) $ 63,093
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows For the year ended December 29, 2018 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (142,315 ) $ 340,401 $ 11,282 $ — $ 209,368 Cash flow from investing activities: Acquisitions, net of cash acquired — (246,017 ) — — (246,017 ) Purchase of property, plant and equipment (7,607 ) (188,435 ) (24,643 ) — (220,685 ) Proceeds from the sale of property, plant, and equipment — 21,263 372 — 21,635 Proceeds from the sale of a business — 21,564 — — 21,564 Other — 3,804 — — 3,804 Net cash used for investing activities (7,607 ) (387,821 ) (24,271 ) — (419,699 ) Cash flow from financing activities: Proceeds from investment by member (146,533 ) 162,148 — — 15,615 Net proceeds from debt issuance 64,500 — — — 64,500 Loans received from and payments made on loans from other Summit Companies 51,696 (65,845 ) 6,647 7,502 — Payments on long-term debt (69,265 ) (15,662 ) (115 ) — (85,042 ) Payments on acquisition-related liabilities — (34,004 ) — — (34,004 ) Debt issuance costs (550 ) — — — (550 ) Distributions from partnership (2,569 ) — — — (2,569 ) Other (879 ) (1,031 ) (33 ) — (1,943 ) Net cash (used in) provided by financing activities (103,600 ) 45,606 6,499 7,502 (43,993 ) Impact of cash on foreign currency — — (724 ) — (724 ) Net decrease in cash (253,522 ) (1,814 ) (7,214 ) 7,502 (255,048 ) Cash — Beginning of period 370,741 10,254 14,933 (12,372 ) 383,556 Cash — End of period $ 117,219 $ 8,440 $ 7,719 $ (4,870 ) $ 128,508 Condensed Consolidating Statements of Cash Flows For the year ended December 30, 2017 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (127,102 ) $ 392,316 $ 29,918 $ — $ 295,132 Cash flow from investing activities: Acquisitions, net of cash acquired (24,538 ) (324,892 ) (25,500 ) — (374,930 ) Purchase of property, plant and equipment (6,196 ) (182,295 ) (5,655 ) — (194,146 ) Proceeds from the sale of property, plant, and equipment — 16,822 250 — 17,072 Other — (471 ) — — (471 ) Net cash used for investing activities (30,734 ) (490,836 ) (30,905 ) — (552,475 ) Cash flow from financing activities: Proceeds from investment by member 40,913 252,911 10,717 — 304,541 Capital issuance costs (627 ) — — — (627 ) Net proceeds from debt issuance 302,000 — — — 302,000 Loans received from and payments made on loans from other Summit Companies 119,858 (108,026 ) (10,126 ) (1,706 ) — Payments on long-term debt (8,463 ) (7,967 ) (8 ) — (16,438 ) Purchase of noncontrolling interests — (532 ) — — (532 ) Payments on acquisition-related liabilities — (32,150 ) — — (32,150 ) Financing costs (6,416 ) — — — (6,416 ) Distributions from partnership (51,986 ) — — — (51,986 ) Other (564 ) (282 ) (20 ) — (866 ) Net cash provided by financing activities 394,715 103,954 563 (1,706 ) 497,526 Impact of cash on foreign currency — — 701 — 701 Net increase in cash 236,879 5,434 277 (1,706 ) 240,884 Cash — Beginning of period 133,862 4,820 14,656 (10,666 ) 142,672 Cash — End of period $ 370,741 $ 10,254 $ 14,933 $ (12,372 ) $ 383,556 Condensed Consolidating Statements of Cash Flows For the year ended December 31, 2016 100% Owned Non- Issuers Guarantors Guarantors Eliminations Consolidated Net cash (used in) provided by operating activities $ (132,328 ) $ 373,588 $ 3,617 $ — $ 244,877 Cash flow from investing activities: Acquisitions, net of cash acquired (42,844 ) (294,114 ) — — (336,958 ) Purchase of property, plant and equipment (5,247 ) (146,336 ) (1,900 ) — (153,483 ) Proceeds from the sale of property, plant, and equipment — 16,606 262 — 16,868 Other — 2,921 — — 2,921 Net cash used for investing activities (48,091 ) (420,923 ) (1,638 ) — (470,652 ) Cash flow from financing activities: Proceeds from investment by member (502,140 ) 529,517 — — 27,377 Capital issuance costs (136 ) — — — (136 ) Net proceeds from debt issuance 354,000 — — — 354,000 Loans received from and payments made on loans from other Summit Companies 440,738 (442,072 ) 400 934 — Payments on long-term debt (110,500 ) (10,202 ) — — (120,702 ) Payments on acquisition-related liabilities (400 ) (29,140 ) — — (29,540 ) Financing costs (5,801 ) — — — (5,801 ) Distributions from partnership (42,192 ) — — — (42,192 ) Other — (16 ) — — (16 ) Net cash provided by financing activities 133,569 48,087 400 934 182,990 Impact of cash on foreign currency — — 69 — 69 Net (decrease) increase in cash (46,850 ) 752 2,448 934 (42,716 ) Cash — Beginning of period 180,712 4,068 12,208 (11,600 ) 185,388 Cash — End of period $ 133,862 $ 4,820 $ 14,656 $ (10,666 ) $ 142,672

Supplementary Data (Unaudited)

Supplementary Data (Unaudited) (Tables)	12 Months Ended
	Dec. 29, 2018
Quarterly Financial Information [Line Items]
Summary of Quarterly Data (Unaudited)	2018 2017 4Q 3Q 2Q 1Q 4Q 3Q 2Q 1Q Net revenue $ 445,090 $ 625,017 $ 549,235 $ 289,916 $ 440,610 $ 574,387 $ 478,368 $ 259,044 Operating income (loss) 28,545 108,167 77,279 (51,525 ) 57,306 113,911 82,444 (32,784 ) Net income (loss) (18,627 ) 73,992 36,913 (55,948 ) 44,510 84,287 52,088 (55,108 ) Net income (loss) attributable to Summit Inc. (19,163 ) 71,289 35,509 (53,729 ) 43,010 81,264 50,000 (52,444 ) Basic earnings per share attributable to Summit Inc. $ (0.17 ) $ 0.64 $ 0.32 $ (0.49 ) $ 0.39 $ 0.74 $ 0.46 $ (0.49 ) Diluted earnings per share attributable to Summit Inc. (0.17 ) 0.64 0.32 (0.49 ) 0.38 0.73 0.46 (0.49 )
Summit Materials, LLC
Quarterly Financial Information [Line Items]
Summary of Quarterly Data (Unaudited)	Supplemental financial information (unaudited) by quarter is as follows for the years ended December 29, 2018 and December 30, 2017 : 2018 2017 4Q 3Q 2Q 1Q 4Q 3Q 2Q 1Q Net revenue $ 445,090 $ 625,017 $ 549,235 $ 289,916 $ 440,610 $ 574,387 $ 478,368 $ 259,044 Operating income (loss) 28,545 108,167 77,279 (51,525 ) 57,306 113,911 82,444 (32,784 ) Net income (loss) (4,596 ) 90,427 46,602 (68,596 ) 52,435 82,633 53,827 (54,854 )

Summary of Organization and S_3

Summary of Organization and Significant Accounting Policies - General Information and Equity Offerings (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 29, 2018segmentplantitemstate	Dec. 30, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Number of operating segments | segment		3
Voting power (as a percent)		97.00%	96.80%	95.00%
Number of states in which the entity operates | item		23
Summit Materials, LLC
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Number of operating segments | segment		3
Number of states in which the entity operates | state		23
Summit Materials, LLC | Ohio Valley Asphalt
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Noncontrolling interest elimination (as a percent)		20.00%
Summit Materials, LLC | Continental Cement
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Noncontrolling interest elimination (as a percent)		30.00%
Summit Holdings LP
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Voting power (as a percent)			100.00%
Cement Plant
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Number of plants | plant		2
Cement Plant | Summit Materials, LLC
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Number of plants | plant		2
Tax Receivable Agreement | Summit Holdings LP
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Percentage of benefits to be paid on tax receivable agreement	85.00%	85.00%
Minimum | Product
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Collection terms		30 days
Maximum | Product
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Collection terms		60 days
Maximum | Service
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements
Collection terms		90 days

Summary of Organization and S_4

Summary of Organization and Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 30, 2018
New Accounting Standards
Other (income) loss, net	$ (15,516)	$ (5,303)	$ 1,361
General and administrative expenses	(253,609)	(242,670)	(243,512)
Summit Materials, LLC
New Accounting Standards
Other (income) loss, net	(15,516)	(5,289)	1,374
General and administrative expenses	$ (253,609)	$ (242,670)	$ (243,512)
Minimum | Scenario, Forecast | Accounting Standards Update 2016-02
New Accounting Standards
Right-of-use asset and liability				$ 30,000
Maximum | Scenario, Forecast | Accounting Standards Update 2016-02
New Accounting Standards
Right-of-use asset and liability				$ 40,000

Acquisitions - Acquisitions by

Acquisitions - Acquisitions by Region (Details) - acquistiion	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
West
Business Acquisition [Line Items]
Number of business acquisitions	5	6	3
East
Business Acquisition [Line Items]
Number of business acquisitions	7	8	5
Cement
Business Acquisition [Line Items]
Number of business acquisitions	0	0	1
Summit Materials, LLC | West
Business Acquisition [Line Items]
Number of business acquisitions	5	6	3
Summit Materials, LLC | East
Business Acquisition [Line Items]
Number of business acquisitions	7	8	5
Summit Materials, LLC | Cement
Business Acquisition [Line Items]
Number of business acquisitions	0	0	1

Acquisitions - Summary of Asset

Acquisitions - Summary of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 1,192,028	$ 1,036,320	$ 782,212
Summit Materials, LLC
Business Acquisition [Line Items]
Goodwill	1,193,028	1,037,320	$ 782,212
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Financial assets	14,769	31,615
Inventories	18,313	8,300
Property, plant and equipment	124,957	160,975
Intangible assets	3,175	161
Other assets	1,539	4,200
Financial liabilities	(13,529)	(15,501)
Other long-term liabilities	(8,125)	(17,610)
Net assets acquired	141,099	172,140
Goodwill	154,120	247,536
Purchase price	295,219	419,676
Acquisition-related liabilities	(49,202)	(43,452)
Other	0	1,294
Net cash paid for acquisitions	246,017	374,930
Series of Individually Immaterial Business Acquisitions [Member] | Summit Materials, LLC
Business Acquisition [Line Items]
Financial assets	14,769	31,615
Inventories	18,313	8,300
Property, plant and equipment	124,957	160,975
Intangible assets	3,175	161
Other assets	1,539	4,200
Financial liabilities	(13,529)	(15,501)
Other long-term liabilities	(8,125)	(17,610)
Net assets acquired	141,099	172,140
Goodwill	154,120	247,536
Purchase price	295,219	419,676
Acquisition-related liabilities	(49,202)	(43,452)
Other	0	1,294
Net cash paid for acquisitions	$ 246,017	$ 374,930

Acquisitions - Contractual Obli

Acquisitions - Contractual Obligations (Details) - USD ($)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Minimum
Remaining payments on contractual obligations
Term of payment for deferred consideration		5 years
Maximum
Remaining payments on contractual obligations
Term of payment for deferred consideration		20 years
Noncompete and Deferred Consideration Agreements
Remaining payments on contractual obligations
2,019		$ 32,960
2,020		31,745
2,021		9,705
2,022		3,411
2,023		2,657
Thereafter		9,640
Total scheduled payments		90,118
Present value adjustments		12,949
Total noncompete obligations and deferred consideration		77,169
Summit Materials, LLC | Minimum
Remaining payments on contractual obligations
Term of payment for deferred consideration	5 years
Summit Materials, LLC | Maximum
Remaining payments on contractual obligations
Term of payment for deferred consideration	20 years
Summit Materials, LLC | Noncompete and Deferred Consideration Agreements
Remaining payments on contractual obligations
2,019		30,460
2,020		29,245
2,021		7,205
2,022		3,411
2,023		2,657
Thereafter		9,640
Total scheduled payments		$ 82,618
Present value adjustments	$ 12,063
Total noncompete obligations and deferred consideration	$ 70,555

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018USD ($)reporting_unit	Dec. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Jan. 02, 2016USD ($)
Goodwill
Number of reporting units with goodwill | reporting_unit	12
Number of reporting units assessed under qualitative assessment | reporting_unit	4
Accumulated impairment losses				$ 68,200
Goodwill	$ 1,192,028	$ 1,036,320	$ 782,212
Goodwill, measurement input, discount rate	0.10
Summit Materials, LLC
Goodwill
Number of reporting units with goodwill | reporting_unit	12
Number of reporting units assessed under qualitative assessment | reporting_unit	4
Accumulated impairment losses				$ 68,200
Goodwill	$ 1,193,028	$ 1,037,320	$ 782,212
Goodwill, measurement input, discount rate	0.10
Austin
Goodwill
Goodwill	$ 18,000
Austin | Summit Materials, LLC
Goodwill
Goodwill	$ 18,000

Goodwill - Summary of Goodwill

Goodwill - Summary of Goodwill by Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Goodwill [Roll Forward]
Beginning balance	$ 1,036,320	$ 782,212
Acquisitions	160,579	249,958
Foreign currency translation adjustments	4,871	(4,150)
Ending balance	1,192,028	1,036,320
Summit Materials, LLC
Goodwill [Roll Forward]
Beginning balance	1,037,320	782,212
Acquisitions	160,579	250,958
Foreign currency translation adjustments	4,871	4,150
Ending balance	1,193,028	1,037,320
West
Goodwill [Roll Forward]
Beginning balance	526,290	334,257
Acquisitions	59,148	187,883
Foreign currency translation adjustments	4,871	(4,150)
Ending balance	580,567	526,290
West | Summit Materials, LLC
Goodwill [Roll Forward]
Beginning balance	527,290	334,257
Acquisitions	59,148	188,883
Foreign currency translation adjustments	4,871	4,150
Ending balance	581,567	527,290
East
Goodwill [Roll Forward]
Beginning balance	305,374	243,417
Acquisitions	101,431	61,957
Foreign currency translation adjustments	0	0
Ending balance	406,805	305,374
East | Summit Materials, LLC
Goodwill [Roll Forward]
Beginning balance	305,374	243,417
Acquisitions	101,431	61,957
Foreign currency translation adjustments	0	0
Ending balance	406,805	305,374
Cement
Goodwill [Roll Forward]
Beginning balance	204,656	204,538
Acquisitions	0	118
Foreign currency translation adjustments	0	0
Ending balance	204,656	204,656
Cement | Summit Materials, LLC
Goodwill [Roll Forward]
Beginning balance	204,656	204,538
Acquisitions	0	118
Foreign currency translation adjustments	0	0
Ending balance	$ 204,656	$ 204,656

Revenue Recognition - By Produc

Revenue Recognition - By Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Revenues	$ 2,101,002	$ 1,932,575	$ 1,626,063
Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	2,101,002	1,932,575	1,626,063
Aggregates
Revenue from External Customer [Line Items]
Revenues	373,824	313,383	264,609
Aggregates | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	373,824	313,383	264,609
Cement
Revenue from External Customer [Line Items]
Revenues	258,876	282,041	250,349
Cement | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	258,876	282,041	250,349
Ready-mix concrete
Revenue from External Customer [Line Items]
Revenues	584,114	492,302	395,917
Ready-mix concrete | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	584,114	492,302	395,917
Asphalt
Revenue from External Customer [Line Items]
Revenues	301,247	285,653	239,419
Asphalt | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	301,247	285,653	239,419
Paving and related services
Revenue from External Customer [Line Items]
Revenues	379,540	371,763	304,041
Paving and related services | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	379,540	371,763	304,041
Other
Revenue from External Customer [Line Items]
Revenues	203,401	187,433	171,728
Other | Summit Materials, LLC
Revenue from External Customer [Line Items]
Revenues	$ 203,401	$ 187,433	$ 171,728

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018USD ($)
Change in Contract with Customer, Asset [Abstract]
Balance—December 30, 2017	$ 9,512
Changes in revenue billed, contract price or cost estimates	8,702
Acquisitions	483
Other	(95)
Balance—December 29, 2018	18,602
Change in Contract with Customer, Liability [Abstract]
Balance—December 30, 2017	15,750
Changes in revenue billed, contract price or cost estimates	(5,052)
Acquisitions	1,179
Other	(37)
Balance—December 29, 2018	11,840
Summit Materials, LLC
Change in Contract with Customer, Asset [Abstract]
Balance—December 30, 2017	9,512
Changes in revenue billed, contract price or cost estimates	(8,702)
Acquisitions	483
Other	(95)
Balance—December 29, 2018	18,602
Change in Contract with Customer, Liability [Abstract]
Balance—December 30, 2017	15,750
Changes in revenue billed, contract price or cost estimates	(5,052)
Acquisitions	1,179
Other	(37)
Balance—December 29, 2018	$ 11,840

Revenue Recognition - Summary o

Revenue Recognition - Summary of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 157,601	$ 137,696
Construction contract receivables	47,994	49,832
Retention receivables	15,010	14,973
Receivables from related parties	629	468
Accounts receivable	221,234	202,969
Less: Allowance for doubtful accounts	(6,716)	(4,639)
Accounts receivable, net	214,518	198,330
Summit Materials, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	157,601	137,696
Construction contract receivables	47,994	49,832
Retention receivables	15,010	14,973
Receivables from related parties	629	468
Accounts receivable	221,234	202,969
Less: Allowance for doubtful accounts	(6,716)	(4,639)
Accounts receivable, net	$ 214,518	$ 198,330
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
General collection and billing period for retention receivables	1 year
Maximum | Summit Materials, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
General collection and billing period for retention receivables	1 year

Inventories - Components of Inv

Inventories - Components of Inventories (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Inventory [Line Items]
Aggregate stockpiles	$ 151,300	$ 126,791
Finished goods	34,993	34,667
Work in process	7,478	7,729
Raw materials	20,080	15,252
Total	213,851	184,439
Summit Materials, LLC
Inventory [Line Items]
Aggregate stockpiles	151,300	126,791
Finished goods	34,993	34,667
Work in process	7,478	7,729
Raw materials	20,080	15,252
Total	$ 213,851	$ 184,439

Property, Plant and Equipment_3

Property, Plant and Equipment, net and Intangibles, net - Components of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,574,383	$ 2,247,265
Less accumulated depreciation, depletion and amortization	(794,251)	(631,841)
Property, plant and equipment, net	1,780,132	1,615,424
Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,574,383	2,247,265
Less accumulated depreciation, depletion and amortization	(794,251)	(631,841)
Property, plant and equipment, net	1,780,132	1,615,424
Land (mineral bearing) and asset retirement costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	323,553	274,083
Land (mineral bearing) and asset retirement costs | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	323,553	274,083
Land (non-mineral bearing)
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	184,029	168,501
Land (non-mineral bearing) | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	184,029	168,501
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 173,559	170,615
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Buildings and improvements | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 173,559	170,615
Buildings and improvements | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Buildings and improvements | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Plants, machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,239,793	1,068,007
Plants, machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Plants, machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Plants, machinery and equipment | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,239,793	1,068,007
Plants, machinery and equipment | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Plants, machinery and equipment | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Mobile equipment and barges
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 468,313	391,256
Mobile equipment and barges | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Mobile equipment and barges | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Mobile equipment and barges | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 468,313	391,256
Mobile equipment and barges | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Mobile equipment and barges | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Truck and auto fleet
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 51,938	47,270
Truck and auto fleet | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Truck and auto fleet | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Truck and auto fleet | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 51,938	47,270
Truck and auto fleet | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Truck and auto fleet | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Landfill airspace and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 49,754	49,480
Landfill airspace and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Landfill airspace and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Landfill airspace and improvements | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 49,754	49,480
Landfill airspace and improvements | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Landfill airspace and improvements | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 39,794	33,314
Office equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Office equipment | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 39,794	33,314
Office equipment | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 43,650	44,739
Construction in progress | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 43,650	$ 44,739
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Other | Summit Materials, LLC | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Other | Summit Materials, LLC | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years

Property, Plant and Equipment_4

Property, Plant and Equipment, net and Intangibles, net - Capital Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization expense	$ 199,600	$ 174,400	$ 144,200
Property, plant and equipment	1,780,132	1,615,424
Property, plant and equipment, accumulated depreciation, depletion and amortization	794,251	631,841
Capital lease obligations, current	15,557	19,276
2,019	17,900
2,020	13,900
2,021	15,300
2,022	3,000
2,023	1,000
General and administrative expenses
Property, Plant and Equipment [Line Items]
Net gain from asset dispositions	12,600	7,500	6,800
Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization expense	199,600	174,400	144,200
Property, plant and equipment	1,780,132	1,615,424
Property, plant and equipment, accumulated depreciation, depletion and amortization	794,251	631,841
Capital lease obligations, current	15,557	19,276
2,019	17,900
2,020	13,900
2,021	15,300
2,022	3,000
2,023	1,000
Summit Materials, LLC | General and administrative expenses
Property, Plant and Equipment [Line Items]
Net gain from asset dispositions	12,600	7,500	$ 6,800
Capital leases for equipment and building
Property, Plant and Equipment [Line Items]
Property, plant and equipment	67,700	51,200
Property, plant and equipment, accumulated depreciation, depletion and amortization	$ 19,300	18,500
Equipment lease term	5 years
Building original lease term	30 years
Capital leases for equipment and building | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 67,700	51,200
Property, plant and equipment, accumulated depreciation, depletion and amortization	$ 19,300	18,500
Equipment lease term	5 years
Building original lease term	30 years
Accrued expenses
Property, Plant and Equipment [Line Items]
Capital lease obligations, current	$ 15,600	19,300
Accrued expenses | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Capital lease obligations, current	15,600	19,300
Noncurrent liabilities
Property, Plant and Equipment [Line Items]
Capital lease obligations, noncurrent	33,600	16,400
Noncurrent liabilities | Summit Materials, LLC
Property, Plant and Equipment [Line Items]
Capital lease obligations, noncurrent	$ 33,600	$ 16,400

Property, Plant and Equipment_5

Property, Plant and Equipment, net and Intangibles, net - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 26,707	$ 23,531
Accumulated Amortization	(8,247)	(6,698)
Net Carrying Amount	18,460	16,833
Amortization expense	1,500	1,300	$ 2,600
Estimated amortization expense
2,018	1,588
2,019	1,510
2,020	1,475
2,021	1,482
2,022	1,349
Thereafter	11,056
Total	18,460	16,833
Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	26,707	23,531
Accumulated Amortization	(8,247)	(6,698)
Net Carrying Amount	18,460	16,833
Amortization expense	1,500	1,300		$ 2,600
Estimated amortization expense
2,018	1,588
2,019	1,510
2,020	1,475
2,021	1,482
2,022	1,349
Thereafter	11,056
Total	18,460	16,833
Leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	19,064	15,888
Accumulated Amortization	(5,259)	(4,178)
Net Carrying Amount	13,805	11,710
Leases | Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	19,064	15,888
Accumulated Amortization	(5,259)	(4,178)
Net Carrying Amount	13,805	11,710
Reserve rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,234	6,234
Accumulated Amortization	(1,940)	(1,625)
Net Carrying Amount	4,294	4,609
Reserve rights | Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,234	6,234
Accumulated Amortization	(1,940)	(1,625)
Net Carrying Amount	4,294	4,609
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,000	1,000
Accumulated Amortization	(858)	(758)
Net Carrying Amount	142	242
Trade names | Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,000	1,000
Accumulated Amortization	(858)	(758)
Net Carrying Amount	142	242
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	409	409
Accumulated Amortization	(190)	(137)
Net Carrying Amount	219	272
Other | Summit Materials, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	409	409
Accumulated Amortization	(190)	(137)
Net Carrying Amount	$ 219	$ 272

Accrued Expenses - Components o

Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Schedule Of Accrued Expenses [Line Items]
Interest	$ 26,223	$ 24,095
Payroll and benefits	15,952	33,915
Capital lease obligations	15,557	19,276
Insurance	13,625	11,455
Non-income taxes	7,442	7,236
Professional fees	1,408	1,717
Other	20,284	18,935
Total	100,491	116,629
Summit Materials, LLC
Schedule Of Accrued Expenses [Line Items]
Interest	26,223	24,095
Payroll and benefits	15,952	33,915
Capital lease obligations	15,557	19,276
Insurance	13,625	11,455
Non-income taxes	7,674	7,467
Professional fees	1,408	1,717
Other	19,590	18,349
Total	$ 100,029	$ 116,274

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017	Nov. 21, 2017	Jun. 01, 2017	Jan. 19, 2017
Debt
Total debt	$ 1,828,159	$ 1,832,455
Current portion of long-term debt	6,354	4,765
Long-term debt	1,821,805	1,827,690
Gross amount	1,830,611
Debt discount	2,452
Summit Materials, LLC
Debt
Total debt	1,828,159	1,832,455
Current portion of long-term debt	6,354	4,765
Long-term debt	1,821,805	1,827,690
Gross amount	1,830,611
Debt discount	2,452
Term Loan, due 2024
Debt
Total debt	629,268	633,805
Gross amount	630,600	635,400
Debt discount	1,300	1,600
Term Loan, due 2024 | Summit Materials, LLC
Debt
Total debt	629,268	633,805
Gross amount	630,600	635,400	$ 635,400		$ 635,400
Debt discount	1,300	1,600
8 1/2% Senior Notes, due 2022
Debt
Total debt	$ 250,000	250,000
Debt instrument interest rate (as a percent)	8.50%
8 1/2% Senior Notes, due 2022 | Summit Materials, LLC
Debt
Total debt	$ 250,000	250,000
Debt instrument interest rate (as a percent)	8.50%
6 1/8% Senior Notes, due 2023
Debt
Total debt	$ 648,891	648,650
Gross amount	650,000	650,000
Debt discount	$ 1,100	1,400
Debt instrument interest rate (as a percent)	6.125%
6 1/8% Senior Notes, due 2023 | Summit Materials, LLC
Debt
Total debt	$ 648,891	648,650
Gross amount	650,000	650,000
Debt discount	$ 1,100	1,400
Debt instrument interest rate (as a percent)	6.125%
5 1/8% Senior Notes, due 2025
Debt
Total debt	$ 300,000	300,000
5 1/8% Senior Notes, due 2025 | Summit Materials, LLC
Debt
Total debt	$ 300,000	$ 300,000
Debt instrument interest rate (as a percent)	5.125%			5.125%

Debt - Schedule of Contractual

Debt - Schedule of Contractual Payments of Long-Term Debt (Details) $ in Thousands	Dec. 29, 2018USD ($)
Contractual payments of long-term debt
2,019	$ 6,354
2,020	7,942
2,021	6,354
2,022	256,354
2,023	656,354
Thereafter	897,253
Total	1,830,611
Less: Original issue net discount	(2,452)
Less: Capitalized loan costs	(14,303)
Total debt	1,813,856
Summit Materials, LLC
Contractual payments of long-term debt
2,019	6,354
2,020	7,942
2,021	6,354
2,022	256,354
2,023	656,354
Thereafter	897,253
Total	1,830,611
Less: Original issue net discount	(2,452)
Less: Capitalized loan costs	(14,303)
Total debt	$ 1,813,856

Debt - Senior Notes Narrative (

Debt - Senior Notes Narrative (Details) - USD ($)	Jun. 01, 2017	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016	Dec. 29, 2018	Nov. 30, 2015	Aug. 31, 2015	Apr. 30, 2015	Mar. 11, 2015
Debt
Write off of deferred financing fees		$ 1,683,000
8 1/2% Senior Notes, due 2022
Debt
Senior notes, interest rate (as a percent)					8.50%
6 1/8% Senior Notes, due 2023
Debt
Senior notes, interest rate (as a percent)					6.125%
10 1/2% Senior Notes, due 2020
Debt
Senior notes, interest rate (as a percent)				10.50%
Senior notes, aggregate principal amount redeemed						$ 153,800,000	$ 183,000,000	$ 288,200,000	$ 288,200,000
Charges on redemption			$ 56,500,000
Prepayment premium			66,600,000
Write off of deferred financing fees			11,900,000
Net benefit from the write-off the original issuance premium and discount			22,000,000
Issuers | 5 1/8% Senior Notes, due 2025
Debt
Debt instrument, face amount	$ 300,000,000
Percentage of par value of senior notes	100.00%
Proceeds net of related fees and expenses	$ 295,400,000
Issuers | 8 1/2% Senior Notes, due 2022
Debt
Debt instrument, face amount			$ 250,000,000
Senior notes, interest rate (as a percent)			8.50%
Percentage of par value of senior notes			100.00%
Proceeds net of related fees and expenses			$ 246,300,000
Issuers | 6 1/8% Senior Notes, due 2023
Debt
Debt instrument, face amount				$ 650,000,000
Senior notes, interest rate (as a percent)				6.125%
Issuers | 6 1/8% Senior Notes, due 2023, issued at par
Debt
Debt instrument, face amount				$ 350,000,000
Issuers | 6 1/8% Senior Notes, due 2023, , issued at 99.375% of par
Debt
Debt instrument, face amount				$ 300,000,000
Percentage of par value of senior notes				99.375%
Summit Materials, LLC
Debt
Write off of deferred financing fees		$ 1,683,000
Summit Materials, LLC | 5 1/8% Senior Notes, due 2025
Debt
Senior notes, interest rate (as a percent)	5.125%				5.125%
Summit Materials, LLC | 8 1/2% Senior Notes, due 2022
Debt
Senior notes, interest rate (as a percent)					8.50%
Summit Materials, LLC | 6 1/8% Senior Notes, due 2023
Debt
Senior notes, interest rate (as a percent)					6.125%
Summit Materials, LLC | 10 1/2% Senior Notes, due 2020
Debt
Senior notes, interest rate (as a percent)				10.50%					10.50%
Senior notes, aggregate principal amount redeemed						$ 153,800,000	$ 183,000,000	$ 288,200,000
Charges on redemption				$ 56,500,000
Prepayment premium				66,600,000
Write off of deferred financing fees				11,900,000
Net benefit from the write-off the original issuance premium and discount				$ 22,000,000

Debt - Senior Secured Credit Fa

Debt - Senior Secured Credit Facilities Narrative (Details)	May 22, 2018USD ($)	Dec. 29, 2018USD ($)	Dec. 30, 2017USD ($)	Nov. 21, 2017USD ($)	Jan. 19, 2017USD ($)
Debt
Outstanding principal amount		$ 1,830,611,000
Financing fees recognized		4,108,000	$ 3,990,000
Term Loan, due 2024
Debt
Outstanding principal amount		630,600,000	635,400,000
Summit Materials, LLC
Debt
Outstanding principal amount		1,830,611,000
Financing fees recognized		4,108,000	3,990,000
Summit Materials, LLC | Term Loan, due 2024
Debt
Debt instrument, face amount		650,000,000
Outstanding principal amount		630,600,000	635,400,000	$ 635,400,000	$ 635,400,000
Summit Materials, LLC | Revolving Credit Facility
Debt
Maximum borrowing capacity		$ 235,000,000
Basis spread on variable rate		0.25%
Amount outstanding		$ 0	$ 0
Remaining borrowing capacity		219,600,000
Summit Materials, LLC | Revolving Credit Facility | Federal funds rate
Debt
Basis spread on variable rate	0.50%
Summit Materials, LLC | Revolving Credit Facility | LIBOR
Debt
Basis spread on variable rate	3.25%
Summit Materials, LLC | Revolving Credit Facility | LIBOR Plus 1%
Debt
Basis spread on variable rate	2.25%
Percentage added to base rate	1.00%
Summit Materials, LLC | Term Loan, due 2022
Debt
Outstanding principal amount	$ 633,800,000				$ 640,300,000
Summit Materials, LLC | Letter of Credit
Debt
Amount outstanding		$ 15,400,000
Summit Materials, LLC | Senior Secured Credit Facilities
Debt
First lien leverage ratio		4.75

Debt - Summary of Activity for

Debt - Summary of Activity for Deferred Financing Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Deferred finance costs
Beginning balance	$ 19,033	$ 18,290
Loan origination fees	550	6,416
Amortization	(4,108)	(3,990)
Write off of deferred financing fees		(1,683)
Ending balance	15,475	19,033
Summit Materials, LLC
Deferred finance costs
Beginning balance	19,033	18,290
Loan origination fees	550	6,416
Amortization	(4,108)	(3,990)
Write off of deferred financing fees		(1,683)
Ending balance	$ 15,475	$ 19,033

Debt - Other Narrative (Details

Debt - Other Narrative (Details)	Jan. 15, 2015CAD ($)	Dec. 29, 2018USD ($)	Dec. 30, 2017USD ($)	Jan. 15, 2015USD ($)
Canadian subsidiary credit agreement, Operating activities
Debt
Revolving credit commitment	$ 6,000,000
Canadian subsidiary credit agreement, Capital equipment
Debt
Revolving credit commitment	500,000
Canadian subsidiary credit agreement, Capital equipment | Summit Materials, LLC
Debt
Revolving credit commitment				$ 500,000
Canadian subsidiary credit agreement, Guarantees
Debt
Revolving credit commitment	$ 400,000
Canadian subsidiary credit agreement, Guarantees | Summit Materials, LLC
Debt
Revolving credit commitment				400,000
Canadian subsidiary credit agreement
Debt
Amount outstanding		$ 0	$ 0
Canadian subsidiary credit agreement | Summit Materials, LLC
Debt
Revolving credit commitment				$ 6,000,000
Amount outstanding		$ 0	$ 0
Prime rate | Canadian subsidiary credit agreement, Operating activities
Debt
Basis spread on variable rate	0.20%
Prime rate | Canadian subsidiary credit agreement, Operating activities | Summit Materials, LLC
Debt
Basis spread on variable rate	0.20%
Prime rate | Canadian subsidiary credit agreement, Capital equipment
Debt
Basis spread on variable rate	0.90%
Prime rate | Canadian subsidiary credit agreement, Capital equipment | Summit Materials, LLC
Debt
Basis spread on variable rate	0.90%

Income Taxes - Components of In

Income Taxes - Components of Income Tax Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Provision for income taxes:
Current	$ 463	$ 2,530	$ 2,835
Deferred	59,284	(286,507)	(8,134)
Income tax expense (benefit)	59,747	(283,977)	(5,299)
Summit Materials, LLC
Provision for income taxes:
Current	463	2,762	2,835
Deferred	9,810	(23,107)	(8,117)
Income tax expense (benefit)	$ 10,273	$ (20,345)	$ (5,282)

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Tax Benefit (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Line Items]
Income tax expense (benefit) at federal statutory tax rate	$ 20,177	$ (55,365)	$ 14,290
Less: Income tax benefit at federal statutory tax rate for LLC entities	(561)	(2,123)	(10,608)
State and local income taxes	4,894	(5,209)	2,490
Permanent differences	(5,537)	(4,410)	(5,902)
Effective tax rate change	4,034	216,904	(1,432)
Unrecognized tax benefits	22,663	0	0
Tax receivable agreement (benefit) expense	(8,282)	104,804	5,228
Change in valuation allowance	17,592	(500,162)	239,008
Impact of LP Unit ownership change	0	(31,790)	(252,456)
Other	4,767	(6,626)	4,083
Income tax expense (benefit)	59,747	(283,977)	(5,299)
Summit Materials, LLC
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Line Items]
Income tax expense (benefit) at federal statutory tax rate	15,563	39,797	19,882
Less: Income tax benefit at federal statutory tax rate for LLC entities	(13,863)	(36,171)	(21,042)
State and local income taxes	1,614	1,751	1,279
Permanent differences	(1,194)	(630)	(1,726)
Effective tax rate change	(1,148)	(24,243)	(1,432)
Unrecognized tax benefits	6,487	0	0
Change in valuation allowance	2,586	0	148
Other	228	(849)	(2,391)
Income tax expense (benefit)	$ 10,273	$ (20,345)	$ (5,282)

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Deferred tax assets (liabilities):
Net intangible assets	$ 275,412	$ 316,950
Accelerated depreciation	(185,020)	(147,943)
Net operating loss	143,234	94,751
Investment in limited partnership	(29,981)	(14,467)
Mining reclamation reserve	1,600	1,239
Inventory purchase accounting adjustments	0	0
Working capital (e.g., accrued compensation, prepaid assets)	(36,932)	(35,237)
Interest expense limitation carryforward	2,586	0
Less valuation allowance	(19,366)	(1,675)	$ (502,839)
Deferred tax assets	225,397	284,092
Less foreign deferred tax liability (included in other noncurrent liabilities)	(5,133)	(3,992)
Net deferred tax asset	220,264	280,100
Summit Materials, LLC
Deferred tax assets (liabilities):
Net intangible assets	(1,734)	(1,256)
Accelerated depreciation	(57,437)	(47,920)
Net operating loss	22,915	20,671
Investment in limited partnership	(16,591)	(10,800)
Mining reclamation reserve	570	488
Working capital (e.g., accrued compensation, prepaid assets)	(1,059)	(1,267)
Interest expense limitation carryforward	2,586	0
Less valuation allowance	(4,261)	(1,675)
Deferred tax liabilities, net	(48,632)	(37,550)
Net deferred tax liability, net	$ (52,893)	$ (39,225)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Sep. 30, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Unrecognized tax benefits				$ 22,663,000	$ 0	$ 0
Deferred tax assets subject to TRA	$ 379,400,000			379,400,000
Income tax expense (benefit)				59,747,000	(283,977,000)	(5,299,000)
Reduction of net deferred tax assets due to change in statutory rate	17,600,000	$ 216,900,000
Unrecognized tax benefits that if recognized would affect the annual effective tax rate	22,700,000			22,700,000
Alternative minimum tax credit	200,000			200,000
Deferred tax asset, valuation allowance	19,366,000	1,675,000		19,366,000	1,675,000	502,839,000
Deferred tax asset, Investment in limited partnership	2,000,000	12,400,000		2,000,000	12,400,000	422,500,000
Tax receivable agreement (benefit) expense				(22,684,000)	271,016,000	14,938,000
Tax receivable agreement liability	309,674,000	331,340,000		309,674,000	331,340,000
Penalties and interest expense				0	0	0
Liability for uncertainty in income taxes	0	0		0	0
Summit Holdings LP
Income Taxes [Line Items]
Distributions to LP Unitholders				100,000	1,800,000
Summit Materials, LLC
Income Taxes [Line Items]
Unrecognized tax benefits				6,487,000	0	0
Income tax expense (benefit)				10,273,000	(20,345,000)	$ (5,282,000)
Operating loss carryforward, reserve	4,300,000	1,700,000		4,300,000	1,700,000
Net operating loss carryforwards	118,500,000			118,500,000
Alternative minimum tax credit	200,000			200,000
Deferred tax asset, valuation allowance	4,261,000	1,675,000		4,261,000	1,675,000
Distributions to LP Unitholders				100,000	49,500,000
Distributions to Summit Inc.				$ 0	47,500,000
Tax Receivable Agreement
Income Taxes [Line Items]
Tax benefit deemed probable			$ 501,800,000
Tax Receivable Agreement | Summit Holdings LP
Income Taxes [Line Items]
Percentage of benefits to be paid on tax receivable agreement			85.00%	85.00%
Other noncurrent liabilities | Tax Receivable Agreement
Income Taxes [Line Items]
Tax receivable agreement liability	310,400,000	331,900,000		$ 310,400,000	331,900,000
Accrued expenses. | Tax Receivable Agreement
Income Taxes [Line Items]
Tax receivable agreement liability	700,000	$ 600,000		700,000	$ 600,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	664,000,000			664,000,000
Federal | Tax Receivable Agreement
Income Taxes [Line Items]
Net operating loss carryforwards	$ 322,500,000			$ 322,500,000

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance—December 30, 2017	$ 0
Additions based on tax position in 2018	22,663
Balance—December 29, 2018	22,663
Summit Materials, LLC
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance—December 30, 2017	0
Additions based on tax position in 2018	6,487
Balance—December 29, 2018	$ 6,487

Incomes Taxes - Deferred Tax As

Incomes Taxes - Deferred Tax Asset Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Valuation Allowance:
Beginning balance	$ (1,675)	$ (502,839)
Additional basis from exchanged LP Units	(99)	(31,790)
Current year increases from operations	(17,592)	0
Release of valuation allowance and other	0	532,954
Ending balance	(19,366)	(1,675)
Summit Materials, LLC
Valuation Allowance:
Beginning balance	(1,675)
Ending balance	$ (4,261)	$ (1,675)

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Basic to Diluted Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Reconciliation of basic to diluted loss per share
Net income attributable to Summit Inc.	$ (19,163)	$ 71,289	$ 35,509	$ (53,729)	$ 43,010	$ 81,264	$ 50,000	$ (52,444)	$ 33,906	$ 121,830	$ 36,783
Weighted average shares of Class A stock outstanding (in shares)											70,355,042
Basic income per share (USD per share)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)	$ 0.39	$ 0.74	$ 0.46	$ (0.49)			$ 0.52
Diluted earnings per share (USD per share)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)	$ 0.38	$ 0.73	$ 0.46	$ (0.49)
LP Units
Reconciliation of basic to diluted loss per share
Anti dilutive shares excluded from calculation of earnings per share									3,512,669	4,371,705	32,327,907
Common Class A
Reconciliation of basic to diluted loss per share
Weighted average shares of Class A stock outstanding (in shares)									111,380,175	108,696,438	70,355,042
Basic income per share (USD per share)									$ 0.30	$ 1.12	$ 0.52
Add: warrants									25,049	42,035	16,123
Weighted average dilutive shares outstanding (in shares)									112,316,646	109,490,898	70,838,508
Diluted earnings per share (USD per share)									$ 0.30	$ 1.11	$ 0.52
Common Class A | LP Units
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									0	0	0
Common Class A | Options
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									282,329	308,355	140,142
Common Class A | Restricted stock
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									459,280	308,221	240,633
Common Class A | Performance Stock Units
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									169,813	135,849	86,568

Stockholders' Equity_Members' I

Stockholders' Equity/Members' Interest - Narrative (Details) $ / shares in Units, $ in Thousands

Jan. 10, 2017USD ($)$ / sharesshares

Aug. 11, 2015USD ($)$ / sharesshares

Jul. 17, 2015USD ($)shares

Mar. 17, 2015USD ($)installmentshares

Mar. 11, 2015USD ($)$ / sharesshares

Dec. 29, 2018USD ($)shares

Dec. 30, 2017USD ($)shares

Dec. 31, 2016USD ($)

Nov. 30, 2015USD ($)

Aug. 31, 2015USD ($)

Apr. 30, 2015USD ($)

Mar. 16, 2015shares

May 31, 2010shares

Subsidiary, Sale of Stock [Line Items]

Proceeds from sale of common stock, net of underwriting discounts

$ 0

$ 237,600

$ 0

Common stock issued (in shares) | shares

10,000,000

Purchase of non-controlling interest

0

$ 532

0

Continental Cement

Subsidiary, Sale of Stock [Line Items]

Aggregate consideration for acquiring noncontrolling interests

$ 64,100

Purchase of non-controlling interest

35,000

Consideration, principal amount of note issued

$ 15,000

Economic interest of redeemable non-controlling interest

70.00%

10 1/2% Senior Notes, due 2020

Subsidiary, Sale of Stock [Line Items]

Senior notes, aggregate principal amount redeemed

$ 288,200

$ 153,800

$ 183,000

$ 288,200

Noninterest Bearing Notes Payable | Continental Cement

Subsidiary, Sale of Stock [Line Items]

Number of annual installments | installment

6

Annual installments amount of non-interest bearing notes payable

$ 2,500

Summit Materials, LLC

Subsidiary, Sale of Stock [Line Items]

Purchase of non-controlling interest

$ 0

$ 532

$ 0

Summit Materials, LLC | 10 1/2% Senior Notes, due 2020

Subsidiary, Sale of Stock [Line Items]

Senior notes, aggregate principal amount redeemed

$ 153,800

$ 183,000

$ 288,200

IPO

Subsidiary, Sale of Stock [Line Items]

Proceeds from sale of common stock, net of underwriting discounts

433,000

IPO | Affiliates of the Sponsors Blackstone Management Partners and Silverhawk Summit | Termination fee paid to related parties

Subsidiary, Sale of Stock [Line Items]

Related party expense

13,800

IPO | 10 1/2% Senior Notes, due 2020

Subsidiary, Sale of Stock [Line Items]

Redemption premium

38,200

Accrued and unpaid interest

$ 5,200

IPO | Continental Cement

Subsidiary, Sale of Stock [Line Items]

Class B units purchased (in shares) | shares

71,428,571

Follow on Public Offering | Summit Holdings LP

Subsidiary, Sale of Stock [Line Items]

Number of Summit LP units purchased by Company, newly issued units (in shares) | shares

3,800,000

3,750,000

Number of Summit LP units purchased by Company from previous owners | shares

18,675,000

Follow on Public Offering | Davenport Assets

Subsidiary, Sale of Stock [Line Items]

Cash paid for acquisitions

$ 80,000

Common Class A

Subsidiary, Sale of Stock [Line Items]

Common stock issued (in shares) | shares

254,102

10,000,000

Common Class A | Continental Cement

Subsidiary, Sale of Stock [Line Items]

Consideration shares issued | shares

1,029,183

Number of class units issued (in shares) | shares

100

Common Class A | IPO

Subsidiary, Sale of Stock [Line Items]

Common stock issued (in shares) | shares

25,555,555

Offering price (in dollars per share) | $ / shares

$ 18

Common Class A | Follow on Public Offering

Subsidiary, Sale of Stock [Line Items]

Proceeds from sale of common stock, net of underwriting discounts

$ 237,600

$ 555,800

Common stock issued (in shares) | shares

10,000,000

22,425,000

Offering price (in dollars per share) | $ / shares

$ 24.05

$ 25.75

Common Class B | Continental Cement

Subsidiary, Sale of Stock [Line Items]

Number of class units issued (in shares) | shares

100,000,000

Economic interest of redeemable non-controlling interest

30.00%

Stockholders' Equity_Members'_2

Stockholders' Equity/Members' Interest - Change in Ownership (Details) - shares	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Increase (Decrease) In Stockholders' Equity [Rollforward]
Beginning balance stockholders' equity (in shares)	114,040,214	102,705,575
Issuance of Shares (in shares)		10,000,000
Exchanges during period (in shares)	1,054,231
Other equity transactions (in shares)		1,334,639
Ending balance stockholders' equity (in shares)	115,094,445	114,040,214	102,705,575
Voting power (as a percent)	97.00%	96.80%	95.00%
LP Units
Increase (Decrease) In Stockholders' Equity [Rollforward]
Number of LP Units outstanding (in shares)	3,689,620	5,151,297
Number of LP Units exchanged	(254,102)	(1,461,677)
Number of LP Units outstanding (in shares)	3,435,518	3,689,620	5,151,297
Common Class A
Increase (Decrease) In Stockholders' Equity [Rollforward]
Beginning balance stockholders' equity (in shares)	110,350,594	97,554,278
Issuance of Shares (in shares)	254,102	10,000,000
Exchanges during period (in shares)	1,054,231	1,461,677
Other equity transactions (in shares)		1,334,639
Ending balance stockholders' equity (in shares)	111,658,927	110,350,594	97,554,278

Stockholders' Equity_Members'_3

Stockholders' Equity/Members' Interest - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Changes in each component of accumulated other comprehensive loss
Beginning balance	$ 1,258,543
Postretirement curtailment adjustment, net of tax		$ 309
Postretirement liability adjustment, net of tax	1,209	605
Foreign currency translation adjustment, net of tax	(6,784)	7,743
Income on cash flow hedges, net of tax	870	978
Ending balance	1,327,741	1,258,543
Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	7,386	(2,249)
Ending balance	2,681	7,386	$ (2,249)
Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	2,364	1,450
Postretirement curtailment adjustment, net of tax		309
Postretirement liability adjustment, net of tax	1,209	605
Ending balance	3,573	2,364	1,450
Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	4,637	(3,106)
Foreign currency translation adjustment, net of tax	(6,784)	7,743
Ending balance	(2,147)	4,637	(3,106)
Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	385	(593)
Income on cash flow hedges, net of tax	870	978
Ending balance	1,255	385	(593)
Summit Materials, LLC
Changes in each component of accumulated other comprehensive loss
Postretirement curtailment adjustment, net of tax		429	0
Postretirement liability adjustment, net of tax	1,661	699	(688)
Foreign currency translation adjustment, net of tax	(9,348)	7,768
Income on cash flow hedges, net of tax	1,206
Summit Materials, LLC | Accumulated Other Comprehensive Operations
Changes in each component of accumulated other comprehensive loss
Beginning balance	(17,135)	(27,444)
Income on cash flow hedges, net of tax		1,413
Ending balance	(23,616)	(17,135)	(27,444)
Summit Materials, LLC | Change in retirement plans
Changes in each component of accumulated other comprehensive loss
Beginning balance	(6,053)	(7,181)
Postretirement curtailment adjustment, net of tax		429
Postretirement liability adjustment, net of tax	1,661
Ending balance	(4,392)	(6,053)	(7,181)
Summit Materials, LLC | Foreign currency translation adjustment
Changes in each component of accumulated other comprehensive loss
Beginning balance	(10,022)	(17,790)
Foreign currency translation adjustment, net of tax	(9,348)	7,768
Ending balance	(19,370)	(10,022)	(17,790)
Summit Materials, LLC | Cash flow hedge adjustments
Changes in each component of accumulated other comprehensive loss
Beginning balance	(1,060)	(2,473)
Income on cash flow hedges, net of tax	1,206	1,413
Ending balance	$ 146	$ (1,060)	$ (2,473)

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Cash payments:
Interest	$ 103,250	$ 96,320	$ 82,540
Income taxes	3,340	1,711	2,645
Non cash financing activities:
Purchase of noncontrolling interest	0	716	0
Stock Dividend	0	(45,023)	(26,939)
Exchange of LP Units to shares of Class A common stock	7,499	41,126	953,752
Summit Materials, LLC
Cash payments:
Interest	103,250	96,320	82,540
Income taxes	3,340	1,711	2,645
Non cash financing activities:
Purchase of noncontrolling interest	$ 0	$ (716)	$ 0

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016	Mar. 11, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 25.4	$ 49.9	$ 19.9
Unrecognized compensation cost		$ 23.3
Weighted average contractual term, unrecognized compensation cost		1 year 9 months 18 days
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Modification charge recognized in general and administrative costs					$ 14.5
2015 Omnibus Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		13,500,000			13,500,000
Shares available for grant (in shares)		6,600,000
2015 Omnibus Equity Incentive Plan | Common Class A | Leverage restoration options issued to holders of Class D interests
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants (in shares)					4,400,000
Exercise price per share under the Omnibus Incentive Plan (in dollars per share)					$ 18
2015 Omnibus Equity Incentive Plan | Common Class A | Warrants issued to holders of Class C interests
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants (in shares)					160,333
Exercise price per share under the Omnibus Incentive Plan (in dollars per share)						$ 18
2015 Omnibus Equity Incentive Plan | General and administrative expenses | Leverage restoration options, performance-vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance target expense				$ 37.7
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during the period (in shares)		689,386
Intrinsic value, units outstanding		$ 11.4
Weighted average remaining contractual term		1 year
Restricted stock | 2015 Omnibus Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during the period (in shares)		38,232	34,928	28,140
Award vesting period		1 year
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		0
Options weighted average exercise price (in dollares per share)		$ 0
Weighted average remaining contractual term		6 years 2 months 12 days
Weighted average strike price, outstanding (in dollars per share)		$ 18.54
Exercisable (in shares)		1,900,000
Intrinsic value, exercisable stock options		$ 11.5
Weighted average strike price, exercisable (in dollars per share)		$ 18.26
Weighed average remaining contractual term, exercisable		5 years 10 months 24 days
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during the period (in shares)		102,842
Award vesting period		3 years
Intrinsic value, units outstanding		$ 3.6
Weighted average remaining contractual term		1 year 1 month 6 days
Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 25.4	$ 49.9	$ 19.9
Unrecognized compensation cost		$ 23.3
Weighted average contractual term, unrecognized compensation cost		1 year 9 months 18 days
Weighed average remaining contractual term, exercisable		5 years 10 months 24 days
Summit Materials, LLC | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during the period (in shares)		689,386
Intrinsic value, units outstanding		$ 11.4
Weighted average remaining contractual term		1 year
Summit Materials, LLC | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		0
Options weighted average exercise price (in dollares per share)		$ 0
Intrinsic value, options outstanding		$ 0
Weighted average remaining contractual term		6 years 2 months 12 days
Options exercisable, weighted average exercise prices (in dollars per share)		$ 18.54
Exercisable (in shares)		1,900,000
Intrinsic value, exercisable stock options		$ 11.5
Weighted average strike price, exercisable (in dollars per share)		$ 18.26
Summit Materials, LLC | Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during the period (in shares)		102,842
Intrinsic value, units outstanding		$ 3.6
Weighted average remaining contractual term		1 year 1 month 6 days
Summit Holdings LP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of LP Units outstanding (in shares)						69,000,000
Summit Holdings LP | Leverage restoration options, time-vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of LP Units outstanding (in shares)						575,256
Share-based compensation expense	$ 1
Summit Holdings LP | Leverage restoration options, performance-vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of LP Units outstanding (in shares)						2,400,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Award Activity (Details)	12 Months Ended
	Dec. 29, 2018$ / sharesshares
Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Beginning balance (in shares)	4,153,613
Options, Granted (in shares)	0
Options, Forfeited (in shares)	(22,566)
Options, Exercised (in shares)	(863,898)
Options, Ending balance (in shares)	3,267,149
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options, Beginning balance (in dollars per share) | $ / shares	$ 9.13
Options, Granted (in dollars per share) | $ / shares	0
Options, Forfeited (in dollars per share) | $ / shares	10.91
Options, Exercised (in dollars per share) | $ / shares	8.88
Options, Ending balance (in dollars per share) | $ / shares	$ 9.09
Options | Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Beginning balance (in shares)	4,153,613
Options, Granted (in shares)	0
Options, Forfeited (in shares)	(22,566)
Options, Exercised (in shares)	(863,898)
Options, Ending balance (in shares)	3,267,149
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options, Beginning balance (in dollars per share) | $ / shares	$ 9.13
Options, Granted (in dollars per share) | $ / shares	0
Options, Forfeited (in dollars per share) | $ / shares	10.91
Options, Exercised (in dollars per share) | $ / shares	8.88
Options, Ending balance (in dollars per share) | $ / shares	$ 9.09
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	508,586
Number of units, granted (in shares)	689,386
Number of units, Forfeited (in shares)	(21,551)
Number of units, Exercised (in shares)	0
Number of units, Vested (in shares)	(252,113)
Number of units, Ending balance (in shares)	924,308
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 20.14
Number of units, Granted (in dollars per share) | $ / shares	28.68
Number of units, Forfeited (in dollars per share) | $ / shares	28.11
Number of units, Exercised (in dollars per share) | $ / shares	0
Number of units, Vested (in dollars per share) | $ / shares	21.95
Number of units, Ending balance (in dollars per share) | $ / shares	$ 24.57
Restricted stock | Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	508,586
Number of units, granted (in shares)	689,386
Number of units, Forfeited (in shares)	(21,551)
Number of units, Vested (in shares)	(252,113)
Number of units, Ending balance (in shares)	924,308
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 20.14
Number of units, Granted (in dollars per share) | $ / shares	28.68
Number of units, Forfeited (in dollars per share) | $ / shares	28.11
Number of units, Vested (in dollars per share) | $ / shares	21.95
Number of units, Ending balance (in dollars per share) | $ / shares	$ 24.57
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	211,455
Number of units, granted (in shares)	102,842
Number of units, Forfeited (in shares)	(19,045)
Number of units, Exercised (in shares)	0
Number of units, Vested (in shares)	0
Number of units, Ending balance (in shares)	295,252
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 23.69
Number of units, Granted (in dollars per share) | $ / shares	40.83
Number of units, Forfeited (in dollars per share) | $ / shares	26.26
Number of units, Exercised (in dollars per share) | $ / shares	0
Number of units, Vested (in dollars per share) | $ / shares	0
Number of units, Ending balance (in dollars per share) | $ / shares	$ 29.12
Performance Stock Units | Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	211,455
Number of units, granted (in shares)	102,842
Number of units, Forfeited (in shares)	(19,045)
Number of units, Ending balance (in shares)	295,252
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 23.69
Number of units, Granted (in dollars per share) | $ / shares	40.83
Number of units, Forfeited (in dollars per share) | $ / shares	26.26
Number of units, Ending balance (in dollars per share) | $ / shares	$ 29.12
Warrants
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	102,778
Number of units, granted (in shares)	0
Number of units, Forfeited (in shares)	0
Number of units, Exercised (in shares)	(2,741)
Number of units, Vested (in shares)	0
Number of units, Ending balance (in shares)	100,037
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 18
Number of units, Exercised (in dollars per share) | $ / shares	18
Number of units, Ending balance (in dollars per share) | $ / shares	$ 18
Warrants | Summit Materials, LLC
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of units, Beginning balance (in shares)	102,778
Number of units, Exercised (in shares)	(2,741)
Number of units, Ending balance (in shares)	100,037
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of units, Beginning balance (in dollars per share) | $ / shares	$ 18
Number of units, Exercised (in dollars per share) | $ / shares	18
Number of units, Ending balance (in dollars per share) | $ / shares	$ 18

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions Used to Estimate the Fair Value of Grants (Details)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, Minimum		2.06%	1.75%
Risk-free interest rate, Maximum		2.31%	1.97%
Volatility (as a percent)		47.00%	48.00%
Expected term		7 years	10 years
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (as a percent)	2.38%	1.45%	0.88%
Volatility (as a percent)	38.00%	39.00%	37.00%
Expected term	3 years	3 years	3 years

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Expense for defined contribution plans	$ 11.2	$ 9.3	$ 8.6
Assumed health care cost trend rates	8.00%
Assumed health care cost, grading		4.50%
Expected contributions in 2019		$ 1
Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Expense for defined contribution plans	$ 11.2	$ 9.3	$ 8.6
Assumed health care cost trend rates		8.00%
Assumed health care cost, grading		4.50%
Expected contributions in 2019	$ 1
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation	30.00%
Equity Securities | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Target allocation	30.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation	63.00%
Fixed Income Securities | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Target allocation	63.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation	5.00%
Cash | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Target allocation	5.00%
Precious metals
Defined Benefit Plan Disclosure [Line Items]
Target allocation	2.00%
Precious metals | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Target allocation	2.00%

Employee Benefit Plans - Obliga

Employee Benefit Plans - Obligations and Funded Status (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Change in fair value of plan assets:
Beginning of period	$ 19,012
End of period	17,449	$ 19,012
Summit Materials, LLC
Change in benefit obligations:
Service cost			$ 279
Interest cost			1,049
Change in fair value of plan assets:
Beginning of period	19,012
End of period	17,449	19,012
Pension Benefits
Change in benefit obligations:
Beginning of period	27,984	27,608
Service cost	67	285	279
Interest cost	898	998	1,049
Actuarial (gain) loss	(3,136)	1,182
Curtailments	0	(430)
Change in plan provision	0	0
Benefits paid	(1,610)	(1,659)
End of period	24,203	27,984	27,608
Change in fair value of plan assets:
Beginning of period	19,012	18,395
Actual return on plan assets	(551)	1,415
Employer contributions	598	861
Benefits paid	(1,610)	(1,659)
End of period	17,449	19,012	18,395
Funded status of plans	(6,754)	(8,972)
Current liabilities	0	0
Noncurrent liabilities	(6,754)	(8,972)
Liability recognized	(6,754)	(8,972)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss	(1,300)	9,341
Prior service cost	(312)	0
Total amount recognized	(1,612)	9,341
Pension Benefits | Summit Materials, LLC
Change in benefit obligations:
Beginning of period	27,984	27,608
Service cost	67	285
Interest cost	898	998
Actuarial (gain) loss	(3,136)	1,182
Curtailments	0
Change in plan provision	0	0
Benefits paid	(1,610)	(1,659)
End of period	24,203	27,984	27,608
Change in fair value of plan assets:
Beginning of period	19,012	18,395
Actual return on plan assets	(551)	1,415
Employer contributions	598	861
Benefits paid	(1,610)	(1,659)
End of period	17,449	19,012	18,395
Funded status of plans	(6,754)	(8,972)
Current liabilities	0	0
Noncurrent liabilities	(6,754)	(8,972)
Liability recognized	(6,754)	(8,972)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss	(1,300)	9,341
Prior service cost	(312)	0
Total amount recognized	(1,612)	9,341
Healthcare & Life Ins
Change in benefit obligations:
Beginning of period	9,793	12,770
Service cost	170	184	230
Interest cost	317	365	470
Actuarial (gain) loss	(173)	(338)
Curtailments	0	0
Change in plan provision	0	(2,325)
Benefits paid	(904)	(863)
End of period	9,203	9,793	12,770
Change in fair value of plan assets:
Beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	904	863
Benefits paid	(904)	(863)
End of period	0	0	0
Funded status of plans	(9,203)	(9,793)
Current liabilities	0	(702)
Noncurrent liabilities	(9,203)	(9,091)
Liability recognized	(9,203)	(9,793)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss	1,995	2,285
Prior service cost	(2,172)	(2,413)
Total amount recognized	(177)	(128)
Healthcare & Life Ins | Summit Materials, LLC
Change in benefit obligations:
Beginning of period	9,793	12,770
Service cost	170	184	230
Interest cost	317	365	470
Actuarial (gain) loss	(173)	(338)
Change in plan provision	0	(2,325)
Benefits paid	(904)	(863)
End of period	9,203	9,793	12,770
Change in fair value of plan assets:
Beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	904	863
Benefits paid	(904)	(863)
End of period	0	0	$ 0
Funded status of plans	(9,203)	(9,793)
Current liabilities	0	(702)
Noncurrent liabilities	(9,203)	(9,091)
Liability recognized	(9,203)	(9,793)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss	1,995	2,285
Prior service cost	(2,172)	(2,413)
Total amount recognized	$ (177)	$ (128)

Employee Benefit Plans - Amount

Employee Benefit Plans - Amounts Recognized in Other Comprehensive (Gain) Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	$ (1,209)	$ (605)
Curtailment benefit		(309)
Summit Materials, LLC
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	(1,661)	(699)	$ 688
Prior service cost			0
Amortization of prior year service cost			0
Curtailment benefit		(429)	0
Amortization of gain			(463)
Adjustment to plan benefits			0
Total amount recognized			225
Pension Benefits
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	(1,300)	1,068	688
Prior service cost	0	0	0
Amortization of prior year service cost	0	0	0
Curtailment benefit	0	(429)	0
Amortization of gain	(312)	(547)	(463)
Adjustment to plan benefits	0	0	0
Total amount recognized	(1,612)	92	225
Pension Benefits | Summit Materials, LLC
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	(1,300)	1,068
Prior service cost	0	0
Amortization of prior year service cost	0	0
Curtailment benefit	0	(429)
Amortization of gain	(312)	(547)
Adjustment to plan benefits	0	0
Total amount recognized	(1,612)	92
Healthcare & Life Ins
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	(172)	(338)	(682)
Prior service cost	0	(572)	64
Amortization of prior year service cost	241	168	174
Curtailment benefit	0	0	0
Amortization of gain	(118)	(64)	(207)
Adjustment to plan benefits	0	(414)	0
Total amount recognized	(49)	(1,220)	(651)
Healthcare & Life Ins | Summit Materials, LLC
Amounts recognized in other comprehensive (income) loss:
Net actuarial (loss) gain	(172)	(338)	(682)
Prior service cost	0	(572)	64
Amortization of prior year service cost	241	168	174
Curtailment benefit	0	0	0
Amortization of gain	(118)	(64)	(207)
Adjustment to plan benefits	0	(414)	0
Total amount recognized	$ (49)	$ (1,220)	$ (651)

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Summit Materials, LLC
Components of net periodic benefit cost:
Service cost			$ 279
Interest cost			1,049
Amortization of gain			463
Expected return on plan assets			(1,386)
Curtailments			0
Net periodic (expense) benefit cost			405
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 67	$ 285	279
Interest cost	898	998	1,049
Amortization of gain	312	547	463
Expected return on plan assets	(1,284)	(1,302)	(1,386)
Curtailments	0	0	0
Amortization of prior service credit	0	0	0
Net periodic (expense) benefit cost	(7)	528	405
Pension Benefits | Summit Materials, LLC
Components of net periodic benefit cost:
Service cost	67	285
Interest cost	898	998
Amortization of gain	312	547
Expected return on plan assets	(1,284)	(1,302)
Curtailments	0	0
Amortization of prior service credit	0	0	0
Net periodic (expense) benefit cost	(7)	528
Healthcare & Life Ins
Components of net periodic benefit cost:
Service cost	170	184	230
Interest cost	317	365	470
Amortization of gain	118	64	207
Expected return on plan assets	0	0	0
Curtailments	0	0	0
Amortization of prior service credit	(241)	(168)	(174)
Net periodic (expense) benefit cost	364	445	733
Healthcare & Life Ins | Summit Materials, LLC
Components of net periodic benefit cost:
Service cost	170	184	230
Interest cost	317	365	470
Amortization of gain	118	64	207
Expected return on plan assets	0	0	0
Curtailments	0	0	0
Amortization of prior service credit	(241)	(168)	(174)
Net periodic (expense) benefit cost	$ 364	$ 445	$ 733

Employee Benefit Plans - Weight

Employee Benefit Plans - Weighted-Average Assumptions Used to Determine Benefit Obligations (Detail)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets, benefit obligation	7.00%	7.00%
Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets, benefit obligation	7.00%	7.00%
Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.90%	3.23%
Pension Benefits | Minimum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.90%	3.23%
Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.02%	3.37%
Pension Benefits | Maximum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.02%	3.37%
Healthcare & Life Ins | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.87%	3.20%
Healthcare & Life Ins | Minimum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.87%	3.20%
Healthcare & Life Ins | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.91%	3.25%
Healthcare & Life Ins | Maximum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.91%	3.25%

Employee Benefit Plans - Weig_2

Employee Benefit Plans - Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets, net periodic benefit cost	7.00%	7.00%	7.30%
Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets, net periodic benefit cost	7.00%	7.00%	7.30%
Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.23%	3.61%	3.74%
Pension Benefits | Minimum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.23%	3.61%	3.74%
Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.37%	3.81%	3.97%
Pension Benefits | Maximum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.37%	3.81%	3.97%
Healthcare & Life Ins | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.20%	3.54%	3.34%
Healthcare & Life Ins | Minimum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.20%	3.54%	3.34%
Healthcare & Life Ins | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.25%	3.65%	3.80%
Healthcare & Life Ins | Maximum | Summit Materials, LLC
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.25%	3.65%	3.80%

Employee Benefit Plans - Effect

Employee Benefit Plans - Effects of One Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total service cost and interest cost components, Increase	$ 31	$ 39
APBO, Increase	765	857
Total service cost and interest cost components, Decrease	(27)	(33)
APBO, Decrease	(690)	(769)
Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total service cost and interest cost components, Increase	31	39
APBO, Increase	765	857
Total service cost and interest cost components, Decrease	(27)	(33)
APBO, Decrease	$ (690)	$ (769)

Employee Benefit Plans - Fair V

Employee Benefit Plans - Fair Value of Company's Pension Plans' Assets (Detail) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	$ 17,449	$ 19,012
Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	17,449	19,012
Intermediate—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,547	3,620
Intermediate—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,547	3,620
Intermediate—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,437	3,872
Intermediate—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,437	3,872
Short-term—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	756	497
Short-term—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	756	497
Short-term—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	957	1,702
Short-term—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	957	1,702
International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,143
International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,143
U.S. Large cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	978	1,765
U.S. Large cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	978	1,765
U.S. Large cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	976	588
U.S. Large cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	976	588
U.S. Mid cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	471	586
U.S. Mid cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	471	586
U.S. Mid cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	496	586
U.S. Mid cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	496	586
U.S. Small cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	463	571
U.S. Small cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	463	571
U.S. Small cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	474	580
U.S. Small cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	474	580
Managed Futures
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	355	392
Managed Futures | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	355	392
International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,004	1,547
International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,004	1,547
Emerging Markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	362
Emerging Markets | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	362
Commodities Broad Basket
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,048	801
Commodities Broad Basket | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,048	801
Cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	982	1,522
Cash | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	982	1,522
Precious metals
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		383
Precious metals | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		383
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	17,449	19,012	$ 18,395
Pension Benefits | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	17,449	19,012	$ 18,395
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	10,222	9,301
Quoted Prices in Active Markets for Identical Assets (Level 1) | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	10,222	9,301
Quoted Prices in Active Markets for Identical Assets (Level 1) | Intermediate—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,547	3,068
Quoted Prices in Active Markets for Identical Assets (Level 1) | Intermediate—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,547	3,068
Quoted Prices in Active Markets for Identical Assets (Level 1) | Intermediate—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Intermediate—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	756	497
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	756	497
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	978	1,765
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	978	1,765
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	976	588
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Large cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	976	588
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	471	586
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	471	586
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	496	586
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Mid cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	496	586
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	463	571
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	463	571
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	474	580
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Small cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	474	580
Quoted Prices in Active Markets for Identical Assets (Level 1) | Managed Futures
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Managed Futures | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	329	677
Quoted Prices in Active Markets for Identical Assets (Level 1) | International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	329	677
Quoted Prices in Active Markets for Identical Assets (Level 1) | Emerging Markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	362
Quoted Prices in Active Markets for Identical Assets (Level 1) | Emerging Markets | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	362
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodities Broad Basket
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	388	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodities Broad Basket | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	388	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	982	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	982	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Precious metals
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		383
Quoted Prices in Active Markets for Identical Assets (Level 1) | Precious metals | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		383
Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	7,227	9,711
Observable Inputs (Level 2) | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	7,227	9,711
Observable Inputs (Level 2) | Intermediate—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	552
Observable Inputs (Level 2) | Intermediate—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	552
Observable Inputs (Level 2) | Intermediate—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,437	3,872
Observable Inputs (Level 2) | Intermediate—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	3,437	3,872
Observable Inputs (Level 2) | Short-term—government
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | Short-term—government | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | Short-term—corporate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	957	1,702
Observable Inputs (Level 2) | Short-term—corporate | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	957	1,702
Observable Inputs (Level 2) | International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,143
Observable Inputs (Level 2) | International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	1,143
Observable Inputs (Level 2) | U.S. Large cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Large cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Large cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Large cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Mid cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Mid cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Mid cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Mid cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Small cap value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Small cap value | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Small cap growth
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | U.S. Small cap growth | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	0
Observable Inputs (Level 2) | Managed Futures
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	355	392
Observable Inputs (Level 2) | Managed Futures | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	355	392
Observable Inputs (Level 2) | International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	675	870
Observable Inputs (Level 2) | International | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	675	870
Observable Inputs (Level 2) | Emerging Markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0
Observable Inputs (Level 2) | Emerging Markets | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0
Observable Inputs (Level 2) | Commodities Broad Basket
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	660	801
Observable Inputs (Level 2) | Commodities Broad Basket | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	660	801
Observable Inputs (Level 2) | Cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	0	1,522
Observable Inputs (Level 2) | Cash | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value	$ 0	1,522
Observable Inputs (Level 2) | Precious metals
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		0
Observable Inputs (Level 2) | Precious metals | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total fair value		$ 0

Employee Benefit Plans - Estima

Employee Benefit Plans - Estimated Benefit Payments (Detail) $ in Thousands	Dec. 29, 2018USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,019	$ 1,736
2,020	1,712
2,021	1,680
2,022	1,678
2,023	1,676
2024 - 2028	7,806
Pension Benefits | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,019	1,736
2,020	1,712
2,021	1,680
2,022	1,678
2,023	1,676
2024 - 2028	7,806
Healthcare & Life Ins
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,019	687
2,020	697
2,021	681
2,022	669
2,023	664
2024 - 2028	3,415
Healthcare & Life Ins | Summit Materials, LLC
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,019	687
2,020	697
2,021	681
2,022	669
2,023	664
2024 - 2028	$ 3,415

Employee Benefit Plans Employee

Employee Benefit Plans Employee Benefit Plans - Multiemployer Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Multiemployer Plans [Line Items]
Contributions of Company	$ 141	$ 134
Construction Industry Laborers Pension Fund
Multiemployer Plans [Line Items]
Contributions of Company	115	104
Operating Engineers Local 101 Pension Plan
Multiemployer Plans [Line Items]
Contributions of Company	26	30
Summit Materials, LLC
Multiemployer Plans [Line Items]
Contributions of Company	141	134
Summit Materials, LLC | Construction Industry Laborers Pension Fund
Multiemployer Plans [Line Items]
Contributions of Company	115	104
Summit Materials, LLC | Operating Engineers Local 101 Pension Plan
Multiemployer Plans [Line Items]
Contributions of Company	$ 26	$ 30

Accrued Mining and Landfill R_3

Accrued Mining and Landfill Reclamation - Narrative (Detail) - USD ($) $ in Millions	Dec. 29, 2018	Dec. 30, 2017
Asset Retirement Obligations [Line Items]
Anticipated costs	$ 92.5	$ 67.9
Accrued expenses
Asset Retirement Obligations [Line Items]
Asset retirement obligation, current	4.1	3.9
Summit Materials, LLC
Asset Retirement Obligations [Line Items]
Anticipated costs	92.5	67.9
Summit Materials, LLC | Accrued expenses
Asset Retirement Obligations [Line Items]
Asset retirement obligation, current	$ 4.1	$ 3.9

Accrued Mining and Landfill R_4

Accrued Mining and Landfill Reclamation - Activity for Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Asset Retirement Obligation, Activity
Beginning balance	$ 24,329	$ 23,906
Acquired obligations	3,937	2,303
Change in cost estimate	2,808	(1,759)
Settlement of reclamation obligations	(1,680)	(1,996)
Accretion expense	1,605	1,875	$ 1,564
Ending balance	30,999	24,329	23,906
Summit Materials, LLC
Asset Retirement Obligation, Activity
Beginning balance	24,329	23,906
Acquired obligations	3,937	2,303
Change in cost estimate	2,808	(1,759)
Settlement of reclamation obligations	(1,680)	(1,996)
Accretion expense	1,605	1,875	1,564
Ending balance	$ 30,999	$ 24,329	$ 23,906

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	12 Months Ended
	Dec. 29, 2018
Loss Contingencies [Line Items]
Term of purchase commitments	1 year

Leasing Arrangements - Addition

Leasing Arrangements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Rent expense, including short-term rentals	$ 25.2	$ 21.7	$ 18.6
Royalty expense recorded in cost of revenue	20.1	18.7	15.6
Summit Materials, LLC
Operating Leased Assets [Line Items]
Rent expense, including short-term rentals	25.2	21.7	18.6
Royalty expense recorded in cost of revenue	$ 20.1	$ 18.7	$ 15.6

Leasing Arrangements - Minimum

Leasing Arrangements - Minimum Contractual Commitments Under Long-Term Operating Leases (Detail) $ in Thousands	Dec. 29, 2018USD ($)
Lease Rental Expenses [Line Items]
2019, Operating Leases	$ 9,479
2020, Operating Leases	8,101
2021, Operating Leases	6,701
2022, Operating Leases	4,279
2023, Operating Leases	3,411
2019, Royalty Agreements	7,124
2020, Royalty Agreements	6,929
2021 Royalty Agreements	6,665
2022, Royalty Agreements	6,742
2023, Royalty Agreements	6,656
Summit Materials, LLC
Lease Rental Expenses [Line Items]
2019, Operating Leases	9,479
2020, Operating Leases	8,101
2021, Operating Leases	6,701
2022, Operating Leases	4,279
2023, Operating Leases	3,411
2019, Royalty Agreements	7,124
2020, Royalty Agreements	6,929
2021 Royalty Agreements	6,665
2022, Royalty Agreements	6,742
2023, Royalty Agreements	$ 6,656

Fair Value of Financial Instr_2

Fair Value of Financial Instruments - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 29, 2018USD ($)
Interest rate derivatives | Term Loan, due 2022 | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Term loan borrowings hedged by derivatives	$ 200
Interest rate derivatives | Term Loan, due 2022 | Cash flow hedges | Summit Materials, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Term loan borrowings hedged by derivatives	$ 200
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	10.00%
Level 3 | Summit Materials, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	10.00%

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	$ 1,394	$ 594
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	5,175	34,301
Cash flow hedges | Interest rate derivatives | Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Cash flow hedge	0	488
Acquisition-related liabilities and Other noncurrent liabilities - Cash flow hedge	0	492
Summit Materials, LLC | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Contingent consideration	1,394	594
Acquisition-related liabilities and Other noncurrent liabilities - Contingent consideration	5,175	34,301
Summit Materials, LLC | Cash flow hedges | Interest rate derivatives | Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of acquisition-related liabilities and Accrued expenses - Cash flow hedge	0	488
Acquisition-related liabilities and Other noncurrent liabilities - Cash flow hedge	$ 0	$ 492

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Financial Instruments
Current portion of debt	$ 6,354	$ 4,765
Summit Materials, LLC
Financial Instruments
Current portion of debt	6,354	4,765
Level 3 | Fair Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	32,876	13,493
Long term portion of deferred consideration and noncompete obligations	44,293	23,834
Level 3 | Carrying Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	32,876	13,493
Long term portion of deferred consideration and noncompete obligations	44,293	23,834
Level 3 | Summit Materials, LLC | Fair Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	30,376	10,993
Long term portion of deferred consideration and noncompete obligations	40,179	17,938
Level 3 | Summit Materials, LLC | Carrying Value
Financial Instruments
Current portion of deferred consideration and noncompete obligations	30,376	10,993
Long term portion of deferred consideration and noncompete obligations	40,179	17,938
Level 2
Financial Instruments
Current portion of debt		4,800
Level 2 | Fair Value
Financial Instruments
Long-term debt	1,777,722	1,893,239
Current portion of debt	6,400
Level 2 | Carrying Value
Financial Instruments
Long-term debt	1,828,159	1,832,455
Level 2 | Summit Materials, LLC
Financial Instruments
Current portion of debt	6,400	4,800
Level 2 | Summit Materials, LLC | Fair Value
Financial Instruments
Long-term debt	1,777,722	1,893,239
Level 2 | Summit Materials, LLC | Carrying Value
Financial Instruments
Long-term debt	$ 1,828,159	$ 1,832,455

Segment Information - Narrative

Segment Information - Narrative (Details)	12 Months Ended
	Dec. 29, 2018segment
Segment Reporting Information [Line Items]
Number of operating segments	3
Summit Materials, LLC
Segment Reporting Information [Line Items]
Number of operating segments	3

Senior Notes' Guarantor and N_3

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Current assets:
Cash and cash equivalents	$ 128,508	$ 383,556	$ 143,392	$ 186,405
Accounts receivable, net	214,518	198,330
Cost and estimated earnings in excess of billings	18,602	9,512
Inventories	213,851	184,439
Other current assets	16,061	7,764
Total current assets	591,540	783,601
Property, plant and equipment, net	1,780,132	1,615,424
Goodwill	1,192,028	1,036,320	782,212
Intangible assets, net	18,460	16,833
Other assets	50,084	51,063
Total assets	3,857,641	3,787,333	2,781,466
Current liabilities:
Current portion of debt	6,354	4,765
Current portion of acquisition-related liabilities	34,270	14,087
Accounts payable	107,702	98,744
Accrued expenses	100,491	116,629
Billings in excess of costs and estimated earnings	11,840	15,750
Total current liabilities	260,657	249,975
Long-term debt	1,807,502	1,810,833
Acquisition-related liabilities	49,468	58,135
Other noncurrent liabilities	88,195	65,329
Total liabilities	2,515,496	2,515,612
Total liabilities and stockholders' equity / member's interest	3,857,641	3,787,333
Summit Materials, LLC
Current assets:
Cash and cash equivalents	128,508	383,556	142,672	185,388
Accounts receivable, net	214,518	198,330
Intercompany receivables	0	0
Cost and estimated earnings in excess of billings	18,602	9,512
Inventories	213,851	184,439
Other current assets	16,061	7,764
Total current assets	591,540	783,601
Property, plant and equipment, net	1,780,132	1,615,424
Goodwill	1,193,028	1,037,320	782,212
Intangible assets, net	18,460	16,833
Other assets	50,084	51,063
Total assets	3,633,244	3,504,241	2,776,420
Current liabilities:
Current portion of debt	6,354	4,765
Current portion of acquisition-related liabilities	31,770	11,587
Accounts payable	109,008	100,637
Accrued expenses	100,029	116,274
Intercompany payables	0	0
Billings in excess of costs and estimated earnings	11,840	15,750
Total current liabilities	259,001	249,013
Long-term debt	1,807,502	1,810,833
Acquisition-related liabilities	45,354	52,239
Other noncurrent liabilities	135,956	100,562
Total liabilities	2,247,813	2,212,647
Total member's interest	1,385,431	1,291,594	876,393	778,292
Total liabilities and stockholders' equity / member's interest	3,633,244	3,504,241
Summit Materials, LLC | Eliminations
Current assets:
Cash and cash equivalents	(4,870)	(12,372)	(10,666)	(11,600)
Accounts receivable, net	(185)	0
Intercompany receivables	(1,125,192)	(1,058,048)
Cost and estimated earnings in excess of billings	0	0
Inventories	0	0
Other current assets	0	0
Total current assets	(1,130,247)	(1,070,420)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	(3,397,794)	(3,003,593)
Total assets	(4,528,041)	(4,074,013)
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	0	0
Accounts payable	(185)	0
Accrued expenses	(4,870)	(12,372)
Intercompany payables	(1,125,192)	(1,058,048)
Billings in excess of costs and estimated earnings	0	0
Total current liabilities	(1,130,247)	(1,070,420)
Long-term debt	0	0
Acquisition-related liabilities	0	0
Other noncurrent liabilities	(171,317)	(171,318)
Total liabilities	(1,301,564)	(1,241,738)
Total member's interest	(3,226,477)	(2,832,275)
Total liabilities and stockholders' equity / member's interest	(4,528,041)	(4,074,013)
Issuers | Summit Materials, LLC | Reportable Legal Entities
Current assets:
Cash and cash equivalents	117,219	370,741	133,862	180,712
Accounts receivable, net	0	0
Intercompany receivables	500,765	573,301
Cost and estimated earnings in excess of billings	0	0
Inventories	0	0
Other current assets	1,953	1,167
Total current assets	619,937	945,209
Property, plant and equipment, net	13,300	9,259
Goodwill	0	0
Intangible assets, net	0	0
Other assets	3,292,851	2,890,674
Total assets	3,926,088	3,845,142
Current liabilities:
Current portion of debt	6,354	4,765
Current portion of acquisition-related liabilities	0	0
Accounts payable	4,712	3,976
Accrued expenses	45,146	47,047
Intercompany payables	673,175	684,057
Billings in excess of costs and estimated earnings	0	0
Total current liabilities	729,387	739,845
Long-term debt	1,807,502	1,810,833
Acquisition-related liabilities	0	0
Other noncurrent liabilities	3,768	2,870
Total liabilities	2,540,657	2,553,548
Total member's interest	1,385,431	1,291,594
Total liabilities and stockholders' equity / member's interest	3,926,088	3,845,142
100% Owned Guarantors | Summit Materials, LLC | Reportable Legal Entities
Current assets:
Cash and cash equivalents	8,440	10,254	4,820	4,068
Accounts receivable, net	199,538	183,139
Intercompany receivables	624,427	484,747
Cost and estimated earnings in excess of billings	17,711	9,264
Inventories	210,149	180,283
Other current assets	11,308	6,354
Total current assets	1,071,573	874,041
Property, plant and equipment, net	1,709,083	1,569,118
Goodwill	1,136,785	976,206
Intangible assets, net	18,460	16,833
Other assets	154,080	162,711
Total assets	4,089,981	3,598,909
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	31,770	11,587
Accounts payable	92,132	89,912
Accrued expenses	57,826	79,372
Intercompany payables	436,564	369,918
Billings in excess of costs and estimated earnings	11,347	15,349
Total current liabilities	629,639	566,138
Long-term debt		0
Acquisition-related liabilities	45,354	52,239
Other noncurrent liabilities	226,137	193,801
Total liabilities	901,130	812,178
Total member's interest	3,188,851	2,786,731
Total liabilities and stockholders' equity / member's interest	4,089,981	3,598,909
Non-Guarantors | Summit Materials, LLC | Reportable Legal Entities
Current assets:
Cash and cash equivalents	7,719	14,933	$ 14,656	$ 12,208
Accounts receivable, net	15,165	15,191
Intercompany receivables	0	0
Cost and estimated earnings in excess of billings	891	248
Inventories	3,702	4,156
Other current assets	2,800	243
Total current assets	30,277	34,771
Property, plant and equipment, net	57,749	37,047
Goodwill	56,243	61,114
Intangible assets, net	0	0
Other assets	947	1,271
Total assets	145,216	134,203
Current liabilities:
Current portion of debt	0	0
Current portion of acquisition-related liabilities	0	0
Accounts payable	12,349	6,749
Accrued expenses	1,927	2,227
Intercompany payables	15,453	4,073
Billings in excess of costs and estimated earnings	493	401
Total current liabilities	30,222	13,450
Long-term debt	0	0
Acquisition-related liabilities	0	0
Other noncurrent liabilities	77,368	75,209
Total liabilities	107,590	88,659
Total member's interest	37,626	45,544
Total liabilities and stockholders' equity / member's interest	$ 145,216	$ 134,203

Segment Information - Financial

Segment Information - Financial Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total revenue	$ 2,101,002	$ 1,932,575	$ 1,626,063
Income (loss) from operations before taxes	96,077	(158,200)	40,827
Interest expense	116,548	108,549	97,536
Depreciation, depletion and amortization	203,305	177,643	147,736
Accretion	1,605	1,875	1,564
IPO/ Legacy equity modification costs	0	0	37,257
Loss on debt financings	149	4,815	0
Tax receivable agreement (benefit) expense	(22,684)	271,016	14,938
Gain on sale of business	(12,108)	0	0
Transaction costs	4,238	7,733	6,797
Management fees and expenses	0	0	(1,379)
Non-cash compensation	25,378	21,140	12,683
Other	(6,247)	1,206	13,388
Total Adjusted EBITDA	406,261	435,777	371,347
Total purchases of property, plant and equipment	220,685	194,146	153,483
Total depreciation, depletion, amortization and accretion	204,910	179,518	149,300
Total assets	3,857,641	3,787,333	2,781,466
Summit Materials, LLC
Segment Reporting Information [Line Items]
Total revenue	2,101,002	1,932,575	1,626,063
Income (loss) from operations before taxes	74,110	113,696	56,805
Interest expense	115,831	107,655	96,483
Depreciation, depletion and amortization	203,305	177,643	147,736
Accretion	1,605	1,875	1,564
IPO/ Legacy equity modification costs	0	0	37,257
Loss on debt financings	149	4,815	0
Gain on sale of business	(12,108)	0	0
Transaction costs	4,238	7,733	6,797
Management fees and expenses	0	0	(1,379)
Non-cash compensation	25,378	21,140	12,683
Other	(6,247)	1,206	13,388
Total Adjusted EBITDA	406,261	435,763	371,334
Total purchases of property, plant and equipment	220,685	194,146	153,483
Total depreciation, depletion, amortization and accretion	204,910	179,518	149,300
Total assets	3,633,244	3,504,241	2,776,420
West
Segment Reporting Information [Line Items]
Total revenue	1,117,066	998,843	813,682
West | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total revenue	1,117,066	998,843	813,682
East
Segment Reporting Information [Line Items]
Total revenue	703,147	629,919	531,294
East | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total revenue	703,147	629,919	531,294
Cement
Segment Reporting Information [Line Items]
Total revenue	280,789	303,813	281,087
Cement | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total revenue	280,789	303,813	281,087
Operating segment
Segment Reporting Information [Line Items]
Total purchases of property, plant and equipment	213,077	187,950	148,235
Total depreciation, depletion, amortization and accretion	202,288	176,917	146,891
Total assets	3,501,727	3,131,724	2,641,816
Operating segment | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total purchases of property, plant and equipment	213,077	187,950	148,235
Total depreciation, depletion, amortization and accretion	202,288	176,917	146,891
Total assets	3,501,727	3,131,724	2,641,816
Operating segment | West
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	188,999	203,590	167,434
Total purchases of property, plant and equipment	120,657	83,591	77,335
Total depreciation, depletion, amortization and accretion	91,794	71,314	65,345
Total assets	1,370,501	1,225,463	902,763
Operating segment | West | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	188,999	203,590	167,434
Total purchases of property, plant and equipment	120,657	83,591	77,335
Total depreciation, depletion, amortization and accretion	91,794	71,314	65,345
Total assets	1,370,501	1,225,463	902,763
Operating segment | East
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	138,032	139,108	126,007
Total purchases of property, plant and equipment	64,384	68,556	45,492
Total depreciation, depletion, amortization and accretion	75,433	67,252	51,540
Total assets	1,253,640	1,035,609	870,613
Operating segment | East | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	138,032	139,108	126,007
Total purchases of property, plant and equipment	64,384	68,556	45,492
Total depreciation, depletion, amortization and accretion	75,433	67,252	51,540
Total assets	1,253,640	1,035,609	870,613
Operating segment | Cement
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	111,394	127,547	112,991
Total purchases of property, plant and equipment	28,036	35,803	25,408
Total depreciation, depletion, amortization and accretion	35,061	38,351	30,006
Total assets	877,586	870,652	868,440
Operating segment | Cement | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	111,394	127,547	112,991
Total purchases of property, plant and equipment	28,036	35,803	25,408
Total depreciation, depletion, amortization and accretion	35,061	38,351	30,006
Total assets	877,586	870,652	868,440
Corporate and other
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	(32,164)	(34,468)	(35,085)
Total purchases of property, plant and equipment	7,608	6,196	5,248
Total depreciation, depletion, amortization and accretion	2,622	2,601	2,409
Total assets	355,914	655,609	139,650
Corporate and other | Summit Materials, LLC
Segment Reporting Information [Line Items]
Total Adjusted EBITDA	(32,164)	(34,482)	(35,098)
Total purchases of property, plant and equipment	7,608	6,196	5,248
Total depreciation, depletion, amortization and accretion	2,622	2,601	2,409
Total assets	$ 131,517	$ 372,517	$ 134,604

Senior Notes' Guarantor and N_4

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Revenues									$ 2,101,002	$ 1,932,575	$ 1,626,063
Cost of revenue (excluding items shown separately below)									1,475,779	1,281,777	1,071,792
Depreciation, depletion, amortization and accretion									204,910	179,518	149,300
Operating income	$ 28,545	$ 108,167	$ 77,279	$ (51,525)	$ 57,306	$ 113,911	$ 82,444	$ (32,784)	162,466	220,877	154,662
Gain on sale of business									(12,108)	0	0
Income (loss) from operations before taxes									96,077	(158,200)	40,827
Income tax expense (benefit)									59,747	(283,977)	(5,299)
Net income	(18,627)	73,992	36,913	(55,948)	44,510	84,287	52,088	(55,108)	36,330	125,777	46,126
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC	(19,163)	71,289	35,509	(53,729)	43,010	81,264	50,000	(52,444)	33,906	121,830	36,783
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									29,201	131,465	37,329
Summit Materials, LLC
Condensed Financial Statements, Captions [Line Items]
Revenues									2,101,002	1,932,575	1,626,063
Cost of revenue (excluding items shown separately below)									1,475,779	1,281,777	1,071,792
General and administrative expenses									257,847	250,403	250,309
Depreciation, depletion, amortization and accretion									204,910	179,518	149,300
Operating income	28,545	108,167	77,279	(51,525)	57,306	113,911	82,444	(32,784)	162,466	220,877	154,662
Other (income) loss, net									(15,367)	(474)	1,374
Interest expense (income)									115,831	107,655	96,483
Gain on sale of business									(12,108)	0	0
Income (loss) from operations before taxes									74,110	113,696	56,805
Income tax expense (benefit)									10,273	(20,345)	(5,282)
Net income	$ (4,596)	$ 90,427	$ 46,602	$ (68,596)	$ 52,435	$ 82,633	$ 53,827	$ (54,854)	63,837	134,041	62,087
Net income (loss) attributable to noncontrolling interest									0	(27)	16
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC									63,837	134,068	62,071
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									57,356	144,377	63,093
Summit Materials, LLC | Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenues									(6,084)	(5,879)	(7,859)
Cost of revenue (excluding items shown separately below)									(6,084)	(5,879)	(7,859)
General and administrative expenses									0	0	0
Depreciation, depletion, amortization and accretion									0	0	0
Operating income									0	0	0
Other (income) loss, net									247,657	309,860	238,874
Interest expense (income)									0	0	0
Gain on sale of business									0
Income (loss) from operations before taxes									(247,657)	(309,860)	(238,874)
Income tax expense (benefit)									0	0	0
Net income										(309,860)	(238,874)
Net income (loss) attributable to noncontrolling interest										(27)	16
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC									(247,657)	(309,833)	(238,890)
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									(254,138)	(299,524)	(237,868)
Summit Materials, LLC | Issuers | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues									0	0	0
Cost of revenue (excluding items shown separately below)									0	0	0
General and administrative expenses									62,376	63,954	91,533
Depreciation, depletion, amortization and accretion									2,622	2,601	2,410
Operating income									(64,998)	(66,555)	(93,943)
Other (income) loss, net									(249,204)	(307,876)	(239,082)
Interest expense (income)									118,857	105,735	83,068
Gain on sale of business									0
Income (loss) from operations before taxes									65,349	135,586	62,071
Income tax expense (benefit)									1,512	1,518	0
Net income										134,068	62,071
Net income (loss) attributable to noncontrolling interest										0	0
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC									63,837	134,068	62,071
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									57,356	144,377	63,093
Summit Materials, LLC | 100% Owned Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues									2,018,428	1,854,434	1,586,858
Cost of revenue (excluding items shown separately below)									1,416,222	1,227,037	1,047,120
General and administrative expenses									184,917	178,023	152,402
Depreciation, depletion, amortization and accretion									197,406	172,738	142,773
Operating income									219,883	276,636	244,563
Other (income) loss, net									(14,643)	(1,925)	1,908
Interest expense (income)									(7,818)	(2,415)	9,956
Gain on sale of business									(12,108)
Income (loss) from operations before taxes									254,452	280,976	232,699
Income tax expense (benefit)									8,226	(23,774)	(5,551)
Net income										304,750	238,250
Net income (loss) attributable to noncontrolling interest										0	0
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC									246,226	304,750	238,250
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									243,359	302,209	239,353
Summit Materials, LLC | Non-Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues									88,658	84,020	47,064
Cost of revenue (excluding items shown separately below)									65,641	60,619	32,531
General and administrative expenses									10,554	8,426	6,374
Depreciation, depletion, amortization and accretion									4,882	4,179	4,117
Operating income									7,581	10,796	4,042
Other (income) loss, net									823	(533)	(326)
Interest expense (income)									4,792	4,335	3,459
Gain on sale of business									0
Income (loss) from operations before taxes									1,966	6,994	909
Income tax expense (benefit)									535	1,911	269
Net income										5,083	640
Net income (loss) attributable to noncontrolling interest										0	0
Net income attributable to Summit Materials, Inc. / member of Summit Materials, LLC									1,431	5,083	640
Comprehensive income (loss) income attributable to member of Summit Materials, LLC									$ 10,779	$ (2,685)	$ (1,485)

Senior Notes' Guarantor and N_5

Senior Notes' Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	$ 209,368	$ 292,183	$ 244,863
Cash flow from investing activities:
Acquisitions, net of cash acquired	(246,017)	(374,930)	(336,958)
Purchase of property, plant and equipment	(220,685)	(194,146)	(153,483)
Proceeds from the sale of property, plant, and equipment	21,635	17,072	16,868
Proceeds from sale of business	21,564	0	0
Other	3,804	(471)	2,921
Net cash used for investing activities	(419,699)	(552,475)	(470,652)
Cash flow from financing activities:
Capital issuance costs	0	(627)	(136)
Net proceeds from debt issuance	64,500	302,000	354,000
Payments on long-term debt	(85,042)	(16,438)	(120,702)
Purchase of noncontrolling interests	0	(532)	0
Payments on acquisition-related liabilities	(36,504)	(34,650)	(32,040)
Debt issuance costs	(550)	(6,416)	(5,801)
Distributions from partnership	(69)	(1,974)	(13,034)
Other	(1,943)	(869)	(20)
Net cash (used in) provided by financing activities	(43,993)	499,755	182,707
Impact of foreign currency on cash	(724)	701	69
Net increase (decrease) in cash	(255,048)	240,164	(43,013)
Cash and cash equivalents—beginning of period	383,556	143,392	186,405
Cash and cash equivalents—end of period	128,508	383,556	143,392
Summit Materials, LLC
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	209,368	295,132	244,877
Cash flow from investing activities:
Acquisitions, net of cash acquired	(246,017)	(374,930)	(336,958)
Purchase of property, plant and equipment	(220,685)	(194,146)	(153,483)
Proceeds from the sale of property, plant, and equipment	21,635	17,072	16,868
Proceeds from sale of business	21,564	0	0
Other	3,804	(471)	2,921
Net cash used for investing activities	(419,699)	(552,475)	(470,652)
Cash flow from financing activities:
Proceeds from investment by member	15,615	304,541	27,377
Capital issuance costs	0	(627)	(136)
Net proceeds from debt issuance	64,500	302,000	354,000
Loans received from and payments made on loans from other Summit Companies	0	0	0
Payments on long-term debt	(85,042)	(16,438)	(120,702)
Purchase of noncontrolling interests	0	(532)	0
Payments on acquisition-related liabilities	(34,004)	(32,150)	(29,540)
Debt issuance costs	(550)	(6,416)	(5,801)
Distributions from partnership	(2,569)	(51,986)	(42,192)
Other	(1,943)	(866)	(16)
Net cash (used in) provided by financing activities	(43,993)	497,526	182,990
Impact of foreign currency on cash	(724)	701	69
Net increase (decrease) in cash	(255,048)	240,884	(42,716)
Cash and cash equivalents—beginning of period	383,556	142,672	185,388
Cash and cash equivalents—end of period	128,508	383,556	142,672
Summit Materials, LLC | Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	0	0	0
Cash flow from investing activities:
Acquisitions, net of cash acquired	0	0	0
Purchase of property, plant and equipment	0	0	0
Proceeds from the sale of property, plant, and equipment	0	0	0
Proceeds from sale of business	0
Other	0	0	0
Net cash used for investing activities	0	0	0
Cash flow from financing activities:
Proceeds from investment by member	0	0	0
Capital issuance costs		0	0
Net proceeds from debt issuance	0	0	0
Loans received from and payments made on loans from other Summit Companies	7,502	(1,706)	934
Payments on long-term debt	0	0	0
Purchase of noncontrolling interests		0
Payments on acquisition-related liabilities	0	0	0
Debt issuance costs	0	0	0
Distributions from partnership	0	0	0
Other	0	0	0
Net cash (used in) provided by financing activities	7,502	(1,706)	934
Impact of foreign currency on cash	0	0	0
Net increase (decrease) in cash	7,502	(1,706)	934
Cash and cash equivalents—beginning of period	(12,372)	(10,666)	(11,600)
Cash and cash equivalents—end of period	(4,870)	(12,372)	(10,666)
Issuers | Summit Materials, LLC | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	(142,315)	(127,102)	(132,328)
Cash flow from investing activities:
Acquisitions, net of cash acquired	0	(24,538)	(42,844)
Purchase of property, plant and equipment	(7,607)	(6,196)	(5,247)
Proceeds from the sale of property, plant, and equipment	0	0	0
Proceeds from sale of business	0
Other	0	0	0
Net cash used for investing activities	(7,607)	(30,734)	(48,091)
Cash flow from financing activities:
Proceeds from investment by member	(146,533)	40,913	(502,140)
Capital issuance costs		(627)	(136)
Net proceeds from debt issuance	64,500	302,000	354,000
Loans received from and payments made on loans from other Summit Companies	51,696	119,858	440,738
Payments on long-term debt	(69,265)	(8,463)	(110,500)
Purchase of noncontrolling interests		0
Payments on acquisition-related liabilities	0	0	(400)
Debt issuance costs	(550)	(6,416)	(5,801)
Distributions from partnership	(2,569)	(51,986)	(42,192)
Other	(879)	(564)	0
Net cash (used in) provided by financing activities	(103,600)	394,715	133,569
Impact of foreign currency on cash	0	0	0
Net increase (decrease) in cash	(253,522)	236,879	(46,850)
Cash and cash equivalents—beginning of period	370,741	133,862	180,712
Cash and cash equivalents—end of period	117,219	370,741	133,862
100% Owned Guarantors | Summit Materials, LLC | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	340,401	392,316	373,588
Cash flow from investing activities:
Acquisitions, net of cash acquired	(246,017)	(324,892)	(294,114)
Purchase of property, plant and equipment	(188,435)	(182,295)	(146,336)
Proceeds from the sale of property, plant, and equipment	21,263	16,822	16,606
Proceeds from sale of business	21,564
Other	3,804	(471)	2,921
Net cash used for investing activities	(387,821)	(490,836)	(420,923)
Cash flow from financing activities:
Proceeds from investment by member	162,148	252,911	529,517
Capital issuance costs		0	0
Net proceeds from debt issuance	0	0	0
Loans received from and payments made on loans from other Summit Companies	(65,845)	(108,026)	(442,072)
Payments on long-term debt	(15,662)	(7,967)	(10,202)
Purchase of noncontrolling interests		(532)
Payments on acquisition-related liabilities	(34,004)	(32,150)	(29,140)
Debt issuance costs	0	0	0
Distributions from partnership	0	0	0
Other	(1,031)	(282)	(16)
Net cash (used in) provided by financing activities	45,606	103,954	48,087
Impact of foreign currency on cash	0	0	0
Net increase (decrease) in cash	(1,814)	5,434	752
Cash and cash equivalents—beginning of period	10,254	4,820	4,068
Cash and cash equivalents—end of period	8,440	10,254	4,820
Non-Guarantors | Summit Materials, LLC | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash (used in) provided by operating activities	11,282	29,918	3,617
Cash flow from investing activities:
Acquisitions, net of cash acquired	0	(25,500)	0
Purchase of property, plant and equipment	(24,643)	(5,655)	(1,900)
Proceeds from the sale of property, plant, and equipment	372	250	262
Proceeds from sale of business	0
Other	0	0	0
Net cash used for investing activities	(24,271)	(30,905)	(1,638)
Cash flow from financing activities:
Proceeds from investment by member	0	10,717	0
Capital issuance costs		0	0
Net proceeds from debt issuance	0	0	0
Loans received from and payments made on loans from other Summit Companies	6,647	(10,126)	400
Payments on long-term debt	(115)	(8)	0
Purchase of noncontrolling interests		0
Payments on acquisition-related liabilities	0	0	0
Debt issuance costs	0	0	0
Distributions from partnership	0	0	0
Other	(33)	(20)	0
Net cash (used in) provided by financing activities	6,499	563	400
Impact of foreign currency on cash	(724)	701	69
Net increase (decrease) in cash	(7,214)	277	2,448
Cash and cash equivalents—beginning of period	14,933	14,656	12,208
Cash and cash equivalents—end of period	$ 7,719	$ 14,933	$ 14,656

Supplementary Data (Unaudited_2

Supplementary Data (Unaudited) - Supplemental Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Condensed Income Statements, Captions [Line Items]
Net revenue	$ 445,090	$ 625,017	$ 549,235	$ 289,916	$ 440,610	$ 574,387	$ 478,368	$ 259,044	$ 1,909,258	$ 1,752,409	$ 1,488,274
Operating income (loss)	28,545	108,167	77,279	(51,525)	57,306	113,911	82,444	(32,784)	162,466	220,877	154,662
Net income	(18,627)	73,992	36,913	(55,948)	44,510	84,287	52,088	(55,108)	36,330	125,777	46,126
Net income (loss) attributable to Summit Inc.	$ (19,163)	$ 71,289	$ 35,509	$ (53,729)	$ 43,010	$ 81,264	$ 50,000	$ (52,444)	33,906	121,830	$ 36,783
Basic income per share (USD per share)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)	$ 0.39	$ 0.74	$ 0.46	$ (0.49)			$ 0.52
Diluted earnings per share (USD per share)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)	$ 0.38	$ 0.73	$ 0.46	$ (0.49)
Summit Materials, LLC
Condensed Income Statements, Captions [Line Items]
Net revenue	$ 445,090	$ 625,017	$ 549,235	$ 289,916	$ 440,610	$ 574,387	$ 478,368	$ 259,044	1,909,258	1,752,409	$ 1,488,274
Operating income (loss)	28,545	108,167	77,279	(51,525)	57,306	113,911	82,444	(32,784)	162,466	220,877	154,662
Net income	$ (4,596)	$ 90,427	$ 46,602	$ (68,596)	$ 52,435	$ 82,633	$ 53,827	$ (54,854)	63,837	134,041	62,087
Net income (loss) attributable to Summit Inc.									$ 63,837	$ 134,068	$ 62,071