Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 383,556	$ 143,392	$ 186,405	$ 13,215
Accounts receivable, net	198,330	162,377
Cost and estimated earnings in excess of billings	9,512	7,450
Inventories	184,439	157,679
Other current assets	7,764	12,800
Total current assets	783,601	483,698
Property, plant and equipment, net	1,615,424	1,446,452
Goodwill	1,036,320	782,212	596,397
Intangible assets	16,833	17,989
Other assets	51,063	46,789
Total assets	3,787,333	2,781,466	2,396,179
Current liabilities:
Current portion of debt	4,765	6,500
Current portion of acquisition-related liabilities	14,087	24,162
Accounts payable	98,744	81,565
Accrued expenses	116,629	111,605
Billings in excess of costs and estimated earnings	15,750	15,456
Total current liabilities	249,975	239,288
Long-term debt	1,810,833	1,514,456
Acquisition-related liabilities	58,135	32,664
Other noncurrent liabilities	65,329	76,874
Total liabilities	2,515,612	1,921,427
Total liabilities and stockholders' equity / member's interest	3,787,333	2,781,466
Summit Materials, LLC
Current assets:
Cash and cash equivalents	383,556	142,672	185,388	13,215
Accounts receivable, net	198,330	162,377
Cost and estimated earnings in excess of billings	9,512	7,450
Inventories	184,439	157,679
Other current assets	7,764	12,800
Total current assets	783,601	482,978
Property, plant and equipment, net	1,615,424	1,446,452
Goodwill	1,037,320	782,212	596,397
Intangible assets	16,833	17,989
Other assets	51,063	46,789
Total assets	3,504,241	2,776,420	2,395,162
Current liabilities:
Current portion of debt	4,765	6,500
Current portion of acquisition-related liabilities	11,587	21,663
Accounts payable	100,637	81,610
Accrued expenses	116,274	110,473
Billings in excess of costs and estimated earnings	15,750	15,456
Total current liabilities	249,013	235,702
Long-term debt	1,810,833	1,514,456
Acquisition-related liabilities	52,239	25,161
Other noncurrent liabilities	100,562	124,708
Total liabilities	2,212,647	1,900,027
Total member's interest	1,291,594	876,393
Total liabilities and stockholders' equity / member's interest	3,504,241	2,776,420
Summit Materials, LLC | Eliminations
Current assets:
Cash and cash equivalents	(12,372)	(10,666)	(11,600)	(7,112)
Accounts receivable, net		(102)
Intercompany receivables	(1,058,048)	(843,434)
Total current assets	(1,070,420)	(854,202)
Other assets	(3,003,593)	(2,374,230)
Total assets	(4,074,013)	(3,228,432)
Current liabilities:
Accounts payable		(102)
Accrued expenses	(12,372)	(10,666)
Intercompany payables	(1,058,048)	(843,434)
Total current liabilities	(1,070,420)	(854,202)
Other noncurrent liabilities	(171,318)	(165,242)
Total liabilities	(1,241,738)	(1,019,444)
Total member's interest	(2,832,275)	(2,208,988)
Total liabilities and stockholders' equity / member's interest	(4,074,013)	(3,228,432)
Summit Materials, LLC | Issuers
Current assets:
Cash and cash equivalents	370,741	133,862	180,712	10,837
Intercompany receivables	573,301	521,658
Other current assets	1,167	1,259
Total current assets	945,209	656,779
Property, plant and equipment, net	9,259	7,033
Other assets	2,890,674	2,293,803
Total assets	3,845,142	2,957,615
Current liabilities:
Current portion of debt	4,765	6,500
Current portion of acquisition-related liabilities		1,000
Accounts payable	3,976	1,497
Accrued expenses	47,047	46,460
Intercompany payables	684,057	509,503
Total current liabilities	739,845	564,960
Long-term debt	1,810,833	1,514,456
Other noncurrent liabilities	2,870	2,395
Total liabilities	2,553,548	2,081,811
Total member's interest	1,291,594	875,804
Total liabilities and stockholders' equity / member's interest	3,845,142	2,957,615
Summit Materials, LLC | Guarantors
Current assets:
Cash and cash equivalents	10,254	4,820	4,068	697
Accounts receivable, net	183,139	155,389
Intercompany receivables	484,747	321,776
Cost and estimated earnings in excess of billings	9,264	6,830
Inventories	180,283	153,374
Other current assets	6,354	11,012
Total current assets	874,041	653,201
Property, plant and equipment, net	1,569,118	1,418,902
Goodwill	976,206	735,490
Intangible assets	16,833	17,989
Other assets	162,711	125,270
Total assets	3,598,909	2,950,852
Current liabilities:
Current portion of acquisition-related liabilities	11,587	20,663
Accounts payable	89,912	76,886
Accrued expenses	79,372	73,807
Intercompany payables	369,918	327,405
Billings in excess of costs and estimated earnings	15,349	15,242
Total current liabilities	566,138	514,003
Acquisition-related liabilities	52,239	25,161
Other noncurrent liabilities	193,801	231,199
Total liabilities	812,178	770,363
Total member's interest	2,786,731	2,180,489
Total liabilities and stockholders' equity / member's interest	3,598,909	2,950,852
Summit Materials, LLC | Non Guarantors
Current assets:
Cash and cash equivalents	14,933	14,656	$ 12,208	$ 8,793
Accounts receivable, net	15,191	7,090
Cost and estimated earnings in excess of billings	248	620
Inventories	4,156	4,305
Other current assets	243	529
Total current assets	34,771	27,200
Property, plant and equipment, net	37,047	20,517
Goodwill	61,114	46,722
Other assets	1,271	1,946
Total assets	134,203	96,385
Current liabilities:
Accounts payable	6,749	3,329
Accrued expenses	2,227	872
Intercompany payables	4,073	6,526
Billings in excess of costs and estimated earnings	401	214
Total current liabilities	13,450	10,941
Other noncurrent liabilities	75,209	56,356
Total liabilities	88,659	67,297
Total member's interest	45,544	29,088
Total liabilities and stockholders' equity / member's interest	$ 134,203	$ 96,385