Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016
Cash flow from operating activities:
Net income (loss)	$ (3,020)	$ (21,029)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	90,781	76,252
Share-based compensation expense	9,424	29,817
Deferred income tax benefit	374	(10,040)
Net gain on asset disposals	(4,052)	(3,717)
Net loss on debt financings	85
Other	710	129
Decrease increase in operating assets, net of acquisitions:
Accounts receivable, net	(68,539)	(55,489)
Inventories	(19,272)	(27,948)
Costs and estimated earnings in excess of billings	(21,571)	(24,542)
Other current assets	3,552	(2,646)
Other assets	(1,565)	(367)
Increase (decrease) in operating liabilities, net of acquisitions:
Accounts payable	28,550	9,682
Accrued expenses	(6,789)	10,343
Billings in excess of costs and estimated earnings	1,252	(3,523)
Other liabilities	1,229	(3,422)
Net cash used in operating activities	11,149	(26,500)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(213,124)	(296,664)
Purchases 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 equity offerings	237,600
Capital issuance costs	(627)	(136)
Proceeds from debt issuances	302,000	321,000
Debt issuance costs	(5,308)	(5,110)
Payments on debt	(9,288)	(63,676)
Payments on acquisition-related liabilities	(17,204)	(25,662)
Distributions	(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
Cash flow from operating activities:
Net income (loss)	(1,027)	(20,484)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion, amortization and accretion	90,314	75,707
Share-based compensation expense	9,424	29,817
Deferred income tax benefit	374	(10,023)
Net gain on asset disposals	(4,052)	(3,717)
Net loss on debt financings	85
Other	710	129
Decrease increase in operating assets, net of acquisitions:
Accounts receivable, net	(68,539)	(55,489)
Inventories	(19,272)	(27,948)
Costs and estimated earnings in excess of billings	(21,571)	(24,542)
Other current assets	3,552	(2,646)
Other assets	(1,582)	(367)
Increase (decrease) in operating liabilities, net of acquisitions:
Accounts payable	27,897	9,682
Accrued expenses	(5,657)	10,326
Billings in excess of costs and estimated earnings	1,252	(3,523)
Other liabilities	(296)	(3,422)
Net cash used in operating activities	11,612	(26,500)
Cash flow from investing activities:
Acquisitions, net of cash acquired	(213,124)	(296,664)
Purchases 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 contributions by member	243,593	113
Capital issuance costs	(627)	(136)
Proceeds from debt issuances	302,000	321,000
Debt issuance costs	(5,308)	(5,110)
Payments on debt	(9,288)	(63,676)
Payments on acquisition-related liabilities	(14,704)	(23,162)
Distributions	(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