Segment Information - Financial Data (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Oct. 01, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Oct. 01, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Information
Number of operating segments | segment			3
Total revenue	$ 634,181	$ 529,437	$ 1,442,551	$ 1,203,090
Adjusted EBITDA	172,701	146,191	321,566	269,332
Interest expense	28,921	25,273	79,876	72,467
Depreciation, depletion and amortization	48,483	39,055	132,374	107,993
Accretion	486	372	1,382	1,202
IPO/Legacy modification costs		12,506		37,257
Loss on debt financings			190
Tax receivable agreement expense	489,215		490,740
Transaction costs	2,581	1,684	6,474	5,290
Non-cash compensation	4,724	3,801	14,148	8,866
Other	(200)	1,085	(346)	4,093
(Loss) income from operations before taxes	(401,509)	62,415	(403,272)	32,164
Total capital expenditures			147,478	121,945
Total depreciation, depletion, amortization and accretion	48,969	39,427	133,756	109,195
Total assets	3,992,792		$ 3,992,792		$ 2,781,466
Summit Materials, LLC
Segment Information
Number of operating segments | segment			3
Total revenue	634,181	529,437	$ 1,442,551	1,203,090
Adjusted EBITDA	172,701	146,191	321,566	269,349
Interest expense	28,708	25,019	79,195	71,668
Depreciation, depletion and amortization	48,483	39,055	132,374	107,993
Accretion	486	372	1,382	1,202
IPO/Legacy modification costs		12,506		37,257
Loss on debt financings			190
Transaction costs	2,581	1,684	6,474	5,290
Non-cash compensation	4,724	3,801	14,148	8,866
Other	(200)	1,085	(346)	4,093
(Loss) income from operations before taxes	87,919	62,669	88,149	32,980
Total capital expenditures			147,478	121,945
Total depreciation, depletion, amortization and accretion	48,969	39,427	133,756	109,195
Total assets	3,515,299		3,515,299		2,776,420
West
Segment Information
Total revenue	327,917	264,874	746,991	614,868
West | Summit Materials, LLC
Segment Information
Total revenue	327,917	264,874	746,991	614,868
East
Segment Information
Total revenue	204,990	175,000	466,222	385,054
East | Summit Materials, LLC
Segment Information
Total revenue	204,990	175,000	466,222	385,054
Cement
Segment Information
Total revenue	101,274	89,563	229,338	203,168
Cement | Summit Materials, LLC
Segment Information
Total revenue	101,274	89,563	229,338	203,168
Operating segment
Segment Information
Total capital expenditures			142,483	118,176
Total depreciation, depletion, amortization and accretion	48,350	38,855	131,816	107,346
Total assets	3,231,961		3,231,961		2,641,816
Operating segment | Summit Materials, LLC
Segment Information
Total capital expenditures			142,483	118,176
Total depreciation, depletion, amortization and accretion	48,350	38,855	131,816	107,346
Total assets	3,231,961		3,231,961		2,641,816
Operating segment | West
Segment Information
Adjusted EBITDA	76,637	63,683	152,856	127,547
Total capital expenditures			64,257	64,350
Total depreciation, depletion, amortization and accretion	18,907	16,492	51,989	48,714
Total assets	1,271,602		1,271,602		902,763
Operating segment | West | Summit Materials, LLC
Segment Information
Adjusted EBITDA	76,637	63,683	152,856	127,547
Total capital expenditures			64,257	64,350
Total depreciation, depletion, amortization and accretion	18,907	16,492	51,989	48,714
Total assets	1,271,602		1,271,602		902,763
Operating segment | East
Segment Information
Adjusted EBITDA	56,397	51,558	99,511	90,405
Total capital expenditures			52,920	37,143
Total depreciation, depletion, amortization and accretion	17,628	14,744	49,939	37,485
Total assets	1,070,346		1,070,346		870,613
Operating segment | East | Summit Materials, LLC
Segment Information
Adjusted EBITDA	56,397	51,558	99,511	90,405
Total capital expenditures			52,920	37,143
Total depreciation, depletion, amortization and accretion	17,628	14,744	49,939	37,485
Total assets	1,070,346		1,070,346		870,613
Operating segment | Cement
Segment Information
Adjusted EBITDA	46,860	40,264	93,328	78,828
Total capital expenditures			25,306	16,683
Total depreciation, depletion, amortization and accretion	11,815	7,619	29,888	21,147
Total assets	890,013		890,013		868,440
Operating segment | Cement | Summit Materials, LLC
Segment Information
Adjusted EBITDA	46,860	40,264	93,328	78,828
Total capital expenditures			25,306	16,683
Total depreciation, depletion, amortization and accretion	11,815	7,619	29,888	21,147
Total assets	890,013		890,013		868,440
Corporate and other
Segment Information
Adjusted EBITDA	(7,193)	(9,314)	(24,129)	(27,448)
Total capital expenditures			4,995	3,769
Total depreciation, depletion, amortization and accretion	619	572	1,940	1,849
Total assets	760,831		760,831		139,650
Corporate and other | Summit Materials, LLC
Segment Information
Adjusted EBITDA	(7,193)	(9,314)	(24,129)	(27,431)
Total capital expenditures			4,995	3,769
Total depreciation, depletion, amortization and accretion	619	572	1,940	1,849
Total assets	283,338		283,338		$ 134,604
Aggregates
Segment Information
Total revenue	90,594	78,274	236,437	201,217
Aggregates | Summit Materials, LLC
Segment Information
Total revenue	90,594	78,274	236,437	201,217
Cement
Segment Information
Total revenue	94,915	81,154	213,243	179,658
Cement | Summit Materials, LLC
Segment Information
Total revenue	94,915	81,154	213,243	179,658
Ready-mixed concrete
Segment Information
Total revenue	139,934	111,141	361,824	288,607
Ready-mixed concrete | Summit Materials, LLC
Segment Information
Total revenue	139,934	111,141	361,824	288,607
Asphalt
Segment Information
Total revenue	115,917	93,551	218,934	182,185
Asphalt | Summit Materials, LLC
Segment Information
Total revenue	115,917	93,551	218,934	182,185
Paving and related services
Segment Information
Total revenue	136,445	113,648	270,449	219,282
Paving and related services | Summit Materials, LLC
Segment Information
Total revenue	136,445	113,648	270,449	219,282
Other
Segment Information
Total revenue	56,376	51,669	141,664	132,141
Other | Summit Materials, LLC
Segment Information
Total revenue	$ 56,376	$ 51,669	$ 141,664	$ 132,141