Note 10 - Property and Equipment (Details Textual)	Dec. 31, 2019 USD ($)
Cost to Complete Construction in Progress	$ 1,556,000

Cost of construction work, which is not yet completed (typically, applied to capital budget items). A CIP item is not depreciated until the asset is placed in service.

No definition available.

Name:	nhc_CostToCompleteConstructionInProgress
Namespace Prefix:	nhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant