Represents stimulus income from government assistance under the CARES Act.

No definition available.

Name:	nhc_GovernmentAssistanceStimulusIncomeCaresAct
Namespace Prefix:	nhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the occupancy percentage in skilled nursing facilities (percentage of beds utilized).

No definition available.

Name:	nhc_OccupancyInSkilledNursingCenters
Namespace Prefix:	nhc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represent the proceeds from Government Assistance Cares Act.

No definition available.

Name:	nhc_ProceedsFromGovernmentAssistanceCaresAct
Namespace Prefix:	nhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents proceeds from Government Assistance Medicare Accelerated and Advance Payment Program.

No definition available.

Name:	nhc_ProceedsFromGovernmentAssistanceMedicareAcceleratedAndAdvancePaymentProgram
Namespace Prefix:	nhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents proceeds from Medicare Accelerated and Advance Payment Program.

No definition available.

Name:	nhc_ProceedsFromMedicareAcceleratedAndAdvancePaymentProgram
Namespace Prefix:	nhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the amount of provider relief funds as of the balance sheet date.

No definition available.

Name:	us-gaap_DebtInstrumentAxis=nhc_MedicareAcceleratedAndAdvancePaymentProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_UnusualRiskOrUncertaintyByNatureAxis=nhc_COVID19Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 3 - Coronavirus Pandemic ("COVID-19") (Details Textual) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Proceeds from Government Assistance Cares Act	$ 58,184,000	$ 58,184,000
Government Assistance Stimulus Income CARES Act	12,132,000		$ 0	$ 36,780,000	$ 0
Provider Relief Funds	$ 21,404,000			21,404,000		$ 0
Proceeds from Medicare Accelerated and Advance Payment Program				51,253,000
Proceeds from Government Assistance Medicare Accelerated and Advance Payment Program				51,253,000
Medicare Accelerated and Advance Payment Program [Member]
Proceeds from Government Assistance Medicare Accelerated and Advance Payment Program				$ 14,854,000
COVID 19 [Member]
Occupancy in Skilled Nursing Centers	81.30%			81.30%