Segment Information - Financial Data (Details) $ in Thousands	12 Months Ended
	Dec. 30, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Jan. 02, 2016 USD ($)
Segment Information
Number of operating segments | segment	3
Total revenue	$ 1,932,575	$ 1,626,063	$ 1,432,297
(Loss) income from operations before taxes	(158,200)	40,827	(19,194)
Interest expense	108,549	97,536	84,629
Depreciation, depletion and amortization	177,643	147,736	118,321
Accretion	1,875	1,564	1,402
IPO/Legacy modification costs		37,257	28,296
Loss on debt financings	4,815		71,631
Tax receivable agreement expense	271,016	14,938
Transaction costs	7,733	6,797	9,519
Management fees and expenses		(1,379)	1,046
Non-cash compensation	21,140	12,683	5,448
Other	1,206	13,388	(13,570)
Total Adjusted EBITDA	435,777	371,347	287,528
Total capital expenditures	194,146	153,483	88,950
Total depreciation, depletion, amortization and accretion	179,518	149,300	119,723
Total assets	$ 3,787,333	2,781,466	2,396,179
Summit Materials, LLC
Segment Information
Number of operating segments | segment	3
Total revenue	$ 1,932,575	1,626,063	1,432,297
(Loss) income from operations before taxes	113,696	56,805	(18,322)
Interest expense	107,655	96,483	83,757
Depreciation, depletion and amortization	177,643	147,736	118,321
Accretion	1,875	1,564	1,402
IPO/Legacy modification costs		37,257	28,296
Loss on debt financings	4,815		71,631
Transaction costs	7,733	6,797	9,519
Management fees and expenses		(1,379)	1,046
Non-cash compensation	21,140	12,683	5,448
Other	1,206	13,388	(13,570)
Total Adjusted EBITDA	435,763	371,334	287,528
Total capital expenditures	194,146	153,483	88,950
Total depreciation, depletion, amortization and accretion	179,518	149,300	119,723
Total assets	3,504,241	2,776,420	2,395,162
Operating segment
Segment Information
Total capital expenditures	187,950	148,235	83,315
Total depreciation, depletion, amortization and accretion	176,917	146,891	117,408
Total assets	3,131,724	2,641,816	2,210,607
Operating segment | Summit Materials, LLC
Segment Information
Total revenue	1,932,575	1,626,063	1,432,297
Total Adjusted EBITDA	139,108	126,007	92,303
Total capital expenditures	187,950	148,235	83,315
Total depreciation, depletion, amortization and accretion	176,917	146,891	117,408
Total assets	3,131,724	2,641,816	2,210,607
Operating segment | West
Segment Information
Total revenue	998,843	813,682	804,503
Total Adjusted EBITDA	203,590	167,434	150,764
Total capital expenditures	83,591	77,335	39,896
Total depreciation, depletion, amortization and accretion	71,314	65,345	53,727
Total assets	1,225,463	902,763	821,479
Operating segment | West | Summit Materials, LLC
Segment Information
Total revenue	998,843	813,682	804,503
Total Adjusted EBITDA	203,590	167,434	150,764
Total capital expenditures	83,591	77,335	39,896
Total depreciation, depletion, amortization and accretion	71,314	65,345	53,727
Total assets	1,225,463	902,763	821,479
Operating segment | East
Segment Information
Total revenue	629,919	531,294	432,310
Total Adjusted EBITDA	139,108	126,007	92,303
Total capital expenditures	68,556	45,492	26,268
Total depreciation, depletion, amortization and accretion	67,252	51,540	38,923
Total assets	1,035,609	870,613	545,187
Operating segment | East | Summit Materials, LLC
Segment Information
Total revenue	629,919	531,294	432,310
Total capital expenditures	68,556	45,492	26,268
Total depreciation, depletion, amortization and accretion	67,252	51,540	38,923
Total assets	1,035,609	870,613	545,187
Operating segment | Cement
Segment Information
Total revenue	303,813	281,087	195,484
Total Adjusted EBITDA	127,547	112,991	74,845
Total capital expenditures	35,803	25,408	17,151
Total depreciation, depletion, amortization and accretion	38,351	30,006	24,758
Total assets	870,652	868,440	843,941
Operating segment | Cement | Summit Materials, LLC
Segment Information
Total revenue	303,813	281,087	195,484
Total Adjusted EBITDA	127,547	112,991	74,845
Total capital expenditures	35,803	25,408	17,151
Total depreciation, depletion, amortization and accretion	38,351	30,006	24,758
Total assets	870,652	868,440	843,941
Corporate and other
Segment Information
Total Adjusted EBITDA	(34,468)	(35,085)	(30,384)
Total capital expenditures	6,196	5,248	5,635
Total depreciation, depletion, amortization and accretion	2,601	2,409	2,315
Total assets	655,609	139,650	185,572
Corporate and other | Summit Materials, LLC
Segment Information
Total Adjusted EBITDA	(34,482)	(35,098)	(30,384)
Total capital expenditures	6,196	5,248	5,635
Total depreciation, depletion, amortization and accretion	2,601	2,409	2,315
Total assets	372,517	134,604	184,555
Aggregates
Segment Information
Total revenue	313,383	264,609	219,040
Aggregates | Summit Materials, LLC
Segment Information
Total revenue	313,383	264,609	219,040
Cement
Segment Information
Total revenue	282,041	250,349	167,696
Cement | Summit Materials, LLC
Segment Information
Total revenue	282,041	250,349	167,696
Ready-mixed concrete
Segment Information
Total revenue	492,302	395,917	350,262
Ready-mixed concrete | Summit Materials, LLC
Segment Information
Total revenue	492,302	395,917	350,262
Asphalt
Segment Information
Total revenue	285,653	239,419	252,031
Asphalt | Summit Materials, LLC
Segment Information
Total revenue	285,653	239,419	252,031
Paving and related services
Segment Information
Total revenue	371,763	304,041	295,995
Paving and related services | Summit Materials, LLC
Segment Information
Total revenue	371,763	304,041	295,995
Other
Segment Information
Total revenue	187,433	171,728	147,273
Other | Summit Materials, LLC
Segment Information
Total revenue	$ 187,433	$ 171,728	$ 147,273