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Earnings Per Share - Schedule of Basic to Diluted Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Reconciliation of basic to diluted loss per share
Net income attributable to Summit Inc.	$ 35,671	$ 55,757	$ 36,410	$ (68,772)	$ (19,163)	$ 71,289	$ 35,509	$ (53,729)	$ 59,066	$ 33,906	$ 121,830
Basic (USD per share)	$ 0.32	$ 0.50	$ 0.32	$ (0.62)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)
Diluted net income attributable to Summit Inc.									$ 59,066	$ 33,906	$ 121,830
Diluted (USD per share)	$ 0.31	$ 0.48	$ 0.32	$ (0.62)	$ (0.17)	$ 0.64	$ 0.32	$ (0.49)
LP Units
Reconciliation of basic to diluted loss per share
Anti dilutive shares excluded from calculation of earnings per share									3,372,706	3,512,669	4,371,705
Common Class A
Reconciliation of basic to diluted loss per share
Weighted average shares of Class A stock outstanding (in shares)									112,204,067	111,380,175	108,696,438
Basic (USD per share)									$ 0.53	$ 0.30	$ 1.12
Add: warrants									4,206	25,049	42,035
Weighted average dilutive shares outstanding (in shares)									112,684,718	112,316,646	109,490,898
Diluted (USD per share)									$ 0.52	$ 0.30	$ 1.11
Common Class A \| Options
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									87,290	282,329	308,355
Common Class A \| Restricted stock
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									342,620	459,280	308,221
Common Class A \| Performance Stock Units
Reconciliation of basic to diluted loss per share
Add: Share-based payment arrangements									46,535	169,813	135,849