Document and Entity Information - USD ($)	12 Months Ended
	Dec. 26, 2020	Mar. 11, 2021	Jun. 27, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 26, 2020
Current Fiscal Year End Date	--12-26
Document Transition Report	false
Entity File Number	1-5039
Entity Registrant Name	WEIS MARKETS, INC.
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	24-0755415
Entity Address, Address Line One	1000 S. Second Street
Entity Address, Address Line Two	P. O. Box 471
Entity Address, City or Town	Sunbury
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	17801-0471
City Area Code	570
Local Phone Number	286-4571
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common stock, no par value
Trading Symbol	WMK
Security Exchange Name	NYSE
Entity Public Float			$ 459,000,000
Entity Common Stock, Shares Outstanding		26,898,443
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE: Selected portions of the Weis Markets, Inc. definitive proxy statement dated March 11, 2021 are incorporated by reference in Part III of this Form 10-K.
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Central Index Key	0000105418