| Document and Entity Information | Aug. 14, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 14, 2024 |
| Entity Registrant Name | NATIONAL HEALTH INVESTORS INC |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 001-10822 |
| Entity Tax Identification Number | 62-1470956 |
| Entity Address Address Line 1 | 222 Robert Rose Drive |
| Entity Address City Or Town | Murfreesboro |
| Entity Address State Or Province | TN |
| Entity Address Postal Zip Code | 37129 |
| City Area Code | 615 |
| Local Phone Number | 890-9100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | NHI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000877860 |
| Amendment Flag | false |
