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Basis of Presentation - Additional Information (Detail)	3 Months Ended			4 Months Ended		6 Months Ended		12 Months Ended
Basis of Presentation - Additional Information (Detail)	Jul. 12, 2025 USD ($)	Jul. 13, 2024 USD ($)	Dec. 30, 2023 USD ($)	Apr. 19, 2025 USD ($)	Apr. 20, 2024 USD ($)	Jul. 12, 2025 USD ($) Segment	Jul. 13, 2024 USD ($)	Dec. 28, 2024 USD ($)	Oct. 05, 2024 USD ($)	Jul. 15, 2023 USD ($)	Jul. 16, 2022 USD ($)
Basis of Presentation [Line Items]
Number of operating segments \| Segment						1
Segment reporting, description						The company has identified two operating segments based on how business activities are managed and evaluated, legacy Flowers Foods and Simple Mills. Simple Mills qualifies as an operating segment as it meets the criteria of being a business and has discrete financial information available that is regularly reviewed by the chief executive officer (the "CEO"), who is the chief operating decision maker (the "CODM"), to assess the performance and allocate resources. As Simple Mills shares similar economic characteristics with legacy Flowers Foods, we aggregate Simple Mills and legacy Flowers Foods as one operating segment for the purposes of determining our one reportable segment.
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]						srt:ChiefExecutiveOfficerMember
Number of reportable segments \| Segment						1
Investment in unconsolidated affiliate	$ 1,481,000					$ 1,481,000		$ 1,481,000
Fair value of investment in unconsolidated affiliate					$ 1,500,000				$ 1,500,000
Asset impairment charges and equipment relocation costs	1,400,000					5,495,000	$ 5,377,000
Impairment charge	0
Recovery related to the sale of equipment						208,000	809,000
Investment impairment loss			$ 5,500,000		$ 4,000,000
Business Process Improvement Cost	$ 471,000	$ 1,606,000				$ 1,362,000	$ 5,289,000
Bailey Street Bakery
Basis of Presentation [Line Items]
Severance costs				$ 1,300,000
Asset impairment charges and equipment relocation costs				$ 6,100,000
Outstanding Trade Receivables \| Wal-Mart/Sam's Club \| Customer Concentration Risk
Basis of Presentation [Line Items]
Concentration risk percentage						19.70%		22.40%
Initial Investment
Basis of Presentation [Line Items]
Fair value of investment in unconsolidated affiliate											$ 9,000,000
Second Investment
Basis of Presentation [Line Items]
Fair value of investment in unconsolidated affiliate										$ 2,000,000