Guarantor and Non-Guarantor Financial Information - Schedule of Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	$ 11,149	$ (26,500)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(213,124)	(296,664)
Purchase of property, plant and equipment	(109,088)	(91,669)
Proceeds from the sale of property, plant, and equipment	8,411	9,442
Other	137	1,500
Net cash used for investing activities	(313,664)	(377,391)
Cash flow from financing activities:
Capital issuance costs	(627)	(136)
Net proceeds from debt issuance	302,000	321,000
Payments on long-term debt	(9,288)	(63,676)
Payments on acquisition-related liabilities	(17,204)	(25,662)
Financing costs	(5,308)	(5,110)
Distributions from partnership	(79)	(373)
Other	4,904	113
Net cash provided by financing activities	511,998	226,156
Impact of cash on foreign currency	188	498
Net increase (decrease) in cash	209,671	(177,237)
Cash and cash equivalents-beginning of period	143,392	186,405
Cash and cash equivalents-end of period	353,063	9,168
Summit Materials, LLC
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	11,612	(26,500)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(213,124)	(296,664)
Purchase of property, plant and equipment	(109,088)	(91,669)
Proceeds from the sale of property, plant, and equipment	8,411	9,442
Other	137	1,500
Net cash used for investing activities	(313,664)	(377,391)
Cash flow from financing activities:
Proceeds from investment by member		113
Proceeds from Partnership Contribution	243,593	113
Capital issuance costs	(627)	(136)
Net proceeds from debt issuance	302,000	321,000
Payments on long-term debt	(9,288)	(63,676)
Payments on acquisition-related liabilities	(14,704)	(23,162)
Financing costs	(5,308)	(5,110)
Distributions from partnership	(2,579)	(2,873)
Other	(832)
Net cash provided by financing activities	512,255	226,156
Impact of cash on foreign currency	188	498
Net increase (decrease) in cash	210,391	(177,237)
Cash and cash equivalents-beginning of period	142,672	185,388
Cash and cash equivalents-end of period	353,063	8,151
Summit Materials, LLC | Eliminations
Cash flow from financing activities:
Loans received from and payments made on loans from other Summit Companies	(2,344)	(2,147)
Net cash provided by financing activities	(2,344)	(2,147)
Net increase (decrease) in cash	(2,344)	(2,147)
Cash and cash equivalents-beginning of period	(10,666)	(11,600)
Cash and cash equivalents-end of period	(13,010)	(13,747)
Summit Materials, LLC | Issuers
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	(57,616)	(101,568)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(15,000)	(60,670)
Purchase of property, plant and equipment	(2,537)	(2,322)
Net cash used for investing activities	(17,537)	(62,992)
Cash flow from financing activities:
Proceeds from investment by member		(448,597)
Proceeds from Partnership Contribution	128,538
Capital issuance costs	(627)	(136)
Net proceeds from debt issuance		321,000
Loans received from and payments made on loans from other Summit Companies	(130,366)	189,466
Payments on long-term debt	(5,250)	(60,250)
Payments on acquisition-related liabilities		(400)
Financing costs	(5,308)	(5,110)
Distributions from partnership	(2,579)	(2,873)
Other	(391)
Net cash provided by financing activities	286,017	(6,900)
Net increase (decrease) in cash	210,864	(171,460)
Cash and cash equivalents-beginning of period	133,862	180,712
Cash and cash equivalents-end of period	344,726	9,252
Summit Materials, LLC | Guarantors
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	49,299	77,254
Cash flow from investing activities:
Acquisitions, net of cash acquired	(172,523)	(235,994)
Purchase of property, plant and equipment	(105,116)	(89,071)
Proceeds from the sale of property, plant, and equipment	8,352	9,422
Other	137
Net cash used for investing activities	(269,150)	(314,143)
Cash flow from financing activities:
Proceeds from investment by member		448,710
Proceeds from Partnership Contribution	104,338
Loans received from and payments made on loans from other Summit Companies	132,577	(187,411)
Payments on long-term debt	(4,038)	(3,426)
Payments on acquisition-related liabilities	(14,704)	(22,762)
Other	(420)
Net cash provided by financing activities	217,753	235,111
Net increase (decrease) in cash	(2,098)	(1,778)
Cash and cash equivalents-beginning of period	4,820	4,068
Cash and cash equivalents-end of period	2,722	2,290
Summit Materials, LLC | Non Guarantors
Condensed Consolidating Statements of Operations
Net cash (used in) provided by operating activities	19,929	(2,186)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(25,601)
Purchase of property, plant and equipment	(1,435)	(276)
Proceeds from the sale of property, plant, and equipment	59	20
Net cash used for investing activities	(26,977)	(256)
Cash flow from financing activities:
Proceeds from Partnership Contribution	10,717
Loans received from and payments made on loans from other Summit Companies	133	92
Other	(21)
Net cash provided by financing activities	10,829	92
Impact of cash on foreign currency	188	498
Net increase (decrease) in cash	3,969	(1,852)
Cash and cash equivalents-beginning of period	14,656	12,208
Cash and cash equivalents-end of period	$ 18,625	$ 10,356