Marketable Securities - SERP Investments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 26, 2022	Mar. 27, 2021
Net Investment Income [Line Items]
Investment Income (Loss) and Interest Expense	$ (881)	$ 1,611
Supplemental Employee Retirement Plan [Member]
Net Investment Income [Line Items]
Investment Income (Loss) and Interest Expense	$ 1,500	$ 775

Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities plus amount of the cost of borrowed funds accounted for as interest expense.

No definition available.

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Namespace Prefix:	wmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration