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