Basis of Presentation - Additional Information (Detail) $ in Thousands	4 Months Ended
Apr. 25, 2026 USD ($) Segment	Apr. 19, 2025 USD ($)	Jan. 03, 2026 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 for 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 purpose 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		$ 1,481
Asset impairment charges and equipment relocation costs	0	$ 5,495
Business Process Improvement Cost	$ 1,241	891
Bailey Street Bakery
Basis of Presentation [Line Items]
Severance costs		1,300
Asset impairment charges and equipment relocation costs		$ 6,100

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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