Consolidated Statements of Changes in Stockholders' Equity / Member's Interest and Redeemable Noncontrolling Interest - USD ($)	Summit Materials, LLC Redeemable Noncontrolling Interest	Summit Materials, LLC Members' equity	Summit Materials, LLC Total Member's Interest	Summit Materials, LLC Noncontrolling Interest in subsidiaries	Summit Materials, LLC Accumulated Earnings/Deficit	Summit Materials, LLC Accumulated Other Comprehensive Operations	Summit Materials, LLC	Redeemable Noncontrolling Interest	Partners' Interest	Noncontrolling Interest in subsidiaries	Accumulated Earnings/Deficit	Accumulated Other Comprehensive Operations	Common Stock Common Class A	Common Stock Common Class B	Additional Paid-in Capital Common Class B	Additional Paid-in Capital	Noncontrolling Interest in Summit Inc.	Common Class A	Common Class B	Total
Beginning Balance at Dec. 28, 2013	$ 24,767,000							$ 24,767,000
Increase (decrease) in redeemable noncontrolling interest
Accretion/ redemption value adjustment	8,145,000
Accretion/ redemption value adjustment								8,145,000
Net income (loss)	2,408,000							2,408,000
Other comprehensive income (loss)	(1,580,000)							(1,580,000)
Ending Balance at Dec. 27, 2014	33,740,000							33,740,000
Beginning Balance at Dec. 28, 2013									$ 285,606,000	$ 1,211,000										$ 286,817,000
Beginning Balance at Dec. 28, 2013		$ 486,896,000	$ 283,551,000	$ 1,211,000	$ (198,511,000)	$ (6,045,000)
Increase (decrease) in stockholders' equity / members' interest and redeemable noncontrolling interest
Contributed capital									24,351,000											24,351,000
Net contributed capital		27,617,000	27,617,000
Accretion/ redemption value adjustment			(8,145,000)		(8,145,000)				(8,145,000)											(8,145,000)
Net income (loss)			(8,690,000)	87,000	(8,777,000)		$ (6,282,000)													(6,282,000)
Net income (loss)									(8,777,000)	87,000										(8,690,000)
Other comprehensive income (loss)			(9,501,000)			(9,501,000)	(11,081,000)													(11,081,000)
Other comprehensive income (loss)									(9,501,000)											(9,501,000)
Share-based compensation		4,222,000	2,239,000		(1,983,000)				2,239,000											2,239,000
Repurchase of member's interest		(88,000)	(88,000)						(88,000)											(88,000)
Ending Balance at Dec. 27, 2014		518,647,000	286,983,000	1,298,000	(217,416,000)	(15,546,000)
Ending Balance at Dec. 27, 2014									285,685,000	1,298,000										286,983,000
Increase (decrease) in redeemable noncontrolling interest
Accretion/ redemption value adjustment								32,252,000
Net income (loss)								(1,890,000)
Ending Balance at Mar. 11, 2015								64,102,000
Increase (decrease) in stockholders' equity / members' interest and redeemable noncontrolling interest
Accretion/ redemption value adjustment									(32,252,000)											(32,252,000)
Net income (loss)									(41,338,000)	(77,000)										(41,415,000)
Other comprehensive income (loss)									(5,249,000)											(5,249,000)
Share-based compensation									424,000											424,000
Ending Balance at Mar. 11, 2015									207,270,000	1,221,000										208,491,000
Beginning Balance at Dec. 27, 2014	33,740,000							33,740,000
Increase (decrease) in redeemable noncontrolling interest
Accretion/ redemption value adjustment	(31,850,000)
Net income (loss)	$ (1,890,000)
Beginning Balance at Dec. 27, 2014									285,685,000	1,298,000										286,983,000
Beginning Balance at Dec. 27, 2014		518,647,000	286,983,000	1,298,000	(217,416,000)	(15,546,000)
Increase (decrease) in stockholders' equity / members' interest and redeemable noncontrolling interest
Net contributed capital		558,939,000	558,939,000
Accretion/ redemption value adjustment			(32,252,000)		(32,252,000)
Net income (loss)			4,246,000	64,000	4,182,000		2,356,000													1,484,000
Other comprehensive income (loss)			(12,920,000)			(12,920,000)	(12,920,000)													(12,920,000)
Share-based compensation		19,899,000	19,899,000
Distributions		(46,603,000)	(46,603,000)
Ending Balance at Jan. 02, 2016										1,362,000	$ 10,870,000	$ (2,795,000)	$ 497,000	$ 690,000		$ 619,003,000	$ 138,233,000			767,860,000
Ending Balance at Jan. 02, 2016		1,050,882,000	778,292,000	1,362,000	(245,486,000)	(28,466,000)	778,292,000
Ending Balance (in shares) at Jan. 02, 2016													49,745,944	69,007,297				49,745,944	69,007,297
Beginning Balance at Mar. 11, 2015								64,102,000
Increase (decrease) in redeemable noncontrolling interest
Purchase of redeemable noncontrolling interest								$ (64,102,000)
Beginning Balance at Mar. 11, 2015									207,270,000	1,221,000										208,491,000
Increase (decrease) in stockholders' equity / members' interest and redeemable noncontrolling interest
Recording of noncontrolling interest upon reorganization									$ (207,270,000)								207,270,000
Net income (loss)										141,000	27,718,000						16,930,000			44,789,000
Issuance of Shares													$ 480,000	$ 690,000	$ (690,000)	512,508,000				512,988,000
Issuance of Shares (in shares)													47,981,653	69,007,397
Other comprehensive income (loss)												(2,795,000)					(4,876,000)			(7,671,000)
Share-based compensation																19,475,000				19,475,000
Share repurchase																1,040,000	(1,040,000)
Share repurchase (in shares)														(100)
Purchase of noncontrolling interests																51,315,000	(51,315,000)
Purchase of redeemable noncontrolling interests (in shares)													1,029,183
Purchase of redeemable noncontrolling interests													$ 10,000			18,515,000				18,525,000
Distributions from partnership																	(28,736,000)			(28,736,000)
Dividend											(16,848,000)		$ 7,000			16,840,000				(1,000)
Dividend (in shares)													735,108
Ending Balance at Jan. 02, 2016										1,362,000	10,870,000	(2,795,000)	$ 497,000	$ 690,000		619,003,000	138,233,000			767,860,000
Ending Balance at Jan. 02, 2016		1,050,882,000	778,292,000	1,362,000	(245,486,000)	(28,466,000)	778,292,000
Ending Balance (in shares) at Jan. 02, 2016													49,745,944	69,007,297				49,745,944	69,007,297
Increase (decrease) in stockholders' equity / members' interest and redeemable noncontrolling interest
Net contributed capital		27,260,000	27,260,000
Net income (loss)			62,087,000	16,000	62,071,000		62,087,000			16,000	36,783,000						9,327,000			46,126,000
LP Unit exchanges													$ 451,000			117,813,000	(118,264,000)
LP Unit exchanges (in shares)													45,124,528
Other comprehensive income (loss)			1,022,000			1,022,000	1,022,000					546,000					476,000			1,022,000
Share-based compensation		51,624,000	49,940,000		(1,684,000)						(1,684,000)					51,624,000				49,940,000
Class B share cancellation														$ (690,000)		690,000
Class B share cancellation (in shares)														(69,007,197)
Distributions		(42,192,000)	(42,192,000)
Distributions from partnership																	(13,034,000)			(13,034,000)
Other													$ 27,058			8,127,000				8,129,000
Other (in shares)													2,000
Other		(16,000)	(16,000)
Dividend											(26,941,000)		$ 11,000			27,047,000	(121,000)			(4,000)
Dividend (in shares)													1,135,692
Ending Balance at Dec. 31, 2016										$ 1,378,000	$ 19,028,000	$ (2,249,000)	$ 961,000			$ 824,304,000	$ 16,617,000			$ 860,039,000
Ending Balance at Dec. 31, 2016		$ 1,087,558,000	$ 876,393,000	$ 1,378,000	$ (185,099,000)	$ (27,444,000)	$ 876,393,000
Ending Balance (in shares) at Dec. 31, 2016													96,033,222	100				96,033,222	100