Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Net income	$ 36,330	$ 125,777	$ 46,126
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	429	0
Postretirement liability adjustment	1,661	699	426
Foreign currency translation adjustment	(9,348)	7,768	2,125
Income (loss) on cash flow hedges	1,206	1,413	(1,529)
Less tax effect of other comprehensive income (loss) items	1,578	(288)	0
Other comprehensive (loss) income:	(4,903)	10,021	1,022
Comprehensive income	31,427	135,798	47,148
Less comprehensive (loss) income attributable to the noncontrolling interest in consolidated subsidiaries	0	(27)	16
Less comprehensive income attributable to Summit Holdings	2,226	4,360	9,803
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	29,201	131,465	37,329
Summit Materials, LLC
Net income	63,837	134,041	62,087
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	429	0
Postretirement liability adjustment	1,661	699	426
Foreign currency translation adjustment	(9,348)	7,768	2,125
Income (loss) on cash flow hedges	1,206	1,413	(1,529)
Other comprehensive (loss) income:	(6,481)	10,309	1,022
Comprehensive income	57,356	144,350	63,109
Less comprehensive (loss) income attributable to the noncontrolling interest in consolidated subsidiaries	0	(27)	16
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	$ 57,356	$ 144,377	$ 63,093