Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Net income	$ 61,123	$ 36,330	$ 125,777
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	0	429
Postretirement liability adjustment	(1,925)	1,661	699
Foreign currency translation adjustment	4,716	(9,348)	7,768
Income (loss) on cash flow hedges	(146)
Income (loss) on cash flow hedges		1,206	1,413
Less tax effect of other comprehensive income items	0	1,578	(288)
Other comprehensive income (loss)	2,645	(4,903)	10,021
Comprehensive income	63,768	31,427	135,798
Less comprehensive income attributable to the noncontrolling interest in consolidated subsidiaries	0	0	(27)
Less comprehensive income attributable to Summit Holdings	3,935	2,226	4,360
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	59,833	29,201	131,465
Summit Materials, LLC
Net income	88,597	63,837	134,041
Other comprehensive income (loss):
Postretirement curtailment adjustment	0	0	429
Postretirement liability adjustment	(1,925)	1,661	699
Foreign currency translation adjustment	4,716	(9,348)	7,768
Income (loss) on cash flow hedges	(146)
Income (loss) on cash flow hedges		1,206	1,413
Other comprehensive income (loss)	2,645	(6,481)	10,309
Comprehensive income	91,242	57,356	144,350
Less comprehensive income attributable to the noncontrolling interest in consolidated subsidiaries	0	0	(27)
Comprehensive income attributable to Summit Materials, Inc. / Summit Materials, LLC	$ 91,242	$ 57,356	$ 144,377