Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Revenue:
Revenue	$ 732,082	$ 694,661	$ 1,665,612	$ 1,609,972
Cost of revenue (excluding items shown separately below):
Net cost of revenue	482,979	471,803	1,155,476	1,130,596
General and administrative expenses	62,344	59,457	190,915	190,975
Depreciation, depletion, amortization and accretion	55,127	53,974	164,140	150,663
Transaction costs	751	1,260	1,449	3,817
Operating income	130,881	108,167	153,632	133,921
Interest expense	28,917	28,889	88,423	86,616
Loss on debt financings	0	0	14,565	149
Gain on sale of business	0	(12,108)	0	(12,108)
Other income, net	(1,875)	(3,371)	(8,354)	(11,942)
Income from operations before taxes	103,839	94,757	58,998	71,206
Income tax expense	45,602	20,765	34,272	16,249
Net income	58,237	73,992	24,726	54,957
Net income attributable to Summit Holdings	2,480	2,703	1,331	1,888
Net income attributable to Summit Inc.	55,757	71,289	23,395	53,069
Summit Materials, LLC
Revenue:
Revenue	732,082	694,661	1,665,612	1,609,972
Cost of revenue (excluding items shown separately below):
Net cost of revenue	482,979	471,803	1,155,476	1,130,596
General and administrative expenses	62,344	59,457	190,915	190,975
Depreciation, depletion, amortization and accretion	55,127	53,974	164,140	150,663
Transaction costs	751	1,260	1,449	3,817
Operating income	130,881	108,167	153,632	133,921
Interest expense	28,800	28,720	88,020	86,066
Loss on debt financings	0	0	14,565	149
Gain on sale of business	0	(12,108)	0	(12,108)
Other income, net	(1,875)	(3,371)	(8,354)	(11,942)
Income from operations before taxes	103,956	94,926	59,401	71,756
Income tax expense	18,757	4,499	12,265	3,323
Net income	85,199	90,427	47,136	68,433
Net income attributable to Summit Inc.	$ 85,199	$ 90,427	$ 47,136	$ 68,433
Class A Common Stock
Earnings per share of Class A common stock:
Basic (usd per share)	$ 0.50	$ 0.64	$ 0.21	$ 0.48
Diluted (usd per share)	$ 0.48	$ 0.64	$ 0.21	$ 0.47
Weighted average shares of Class A common stock:
Basic (in shares)	112,179,137	111,641,344	112,020,275	111,288,211
Diluted (in shares)	115,505,122	111,940,067	112,497,610	112,472,724
Product
Revenue:
Revenue	$ 554,721	$ 512,822	$ 1,293,999	$ 1,229,596
Cost of revenue (excluding items shown separately below):
Net cost of revenue	338,119	321,586	846,702	814,166
Product | Summit Materials, LLC
Revenue:
Revenue	554,721	512,822	1,293,999	1,229,596
Cost of revenue (excluding items shown separately below):
Net cost of revenue	338,119	321,586	846,702	814,166
Service
Revenue:
Revenue	111,126	112,195	230,389	234,572
Cost of revenue (excluding items shown separately below):
Net cost of revenue	78,625	80,573	167,550	170,626
Service | Summit Materials, LLC
Revenue:
Revenue	111,126	112,195	230,389	234,572
Cost of revenue (excluding items shown separately below):
Net cost of revenue	78,625	80,573	167,550	170,626
Excluding delivery and subcontract revenue
Revenue:
Revenue	665,847	625,017	1,524,388	1,464,168
Cost of revenue (excluding items shown separately below):
Net cost of revenue	416,744	402,159	1,014,252	984,792
Excluding delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	665,847	625,017	1,524,388	1,464,168
Cost of revenue (excluding items shown separately below):
Net cost of revenue	416,744	402,159	1,014,252	984,792
Delivery and subcontract revenue
Revenue:
Revenue	66,235	69,644	141,224	145,804
Cost of revenue (excluding items shown separately below):
Net cost of revenue	66,235	69,644	141,224	145,804
Delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	66,235	69,644	141,224	145,804
Cost of revenue (excluding items shown separately below):
Net cost of revenue	$ 66,235	$ 69,644	$ 141,224	$ 145,804