Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2025	Nov. 03, 2025
Document Information [Line Items]
Entity Central Index Key	0001047335
Entity Registrant Name	NATIONAL HEALTHCARE CORP
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2025
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-13489
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	52-2057472
Entity Address, Address Line One	100 E. Vine Street
Entity Address, City or Town	Murfreesboro
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	37130
City Area Code	615
Local Phone Number	890–2020
Title of 12(b) Security	Common, $0.01 par value
Trading Symbol	NHC
Security Exchange Name	NYSEAMER
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		15,515,253