Summary of Total Cost and Employer Contributions (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Oct. 05, 2019	Oct. 03, 2020	Oct. 05, 2019
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan, Plan Name [Extensible List]	flo:FourZeroOneKRetirementSavingsPlanMember	flo:FourZeroOneKRetirementSavingsPlanMember	flo:FourZeroOneKRetirementSavingsPlanMember	flo:FourZeroOneKRetirementSavingsPlanMember
Total cost and employer contributions	$ 6,355	$ 6,264	$ 21,577	$ 21,137