| Cover | Feb. 21, 2025 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 21, 2025 |
| Entity File Number | 811-05399 |
| Entity Registrant Name | The New America High Income Fund Inc. |
| Entity Central Index Key | 0000825345 |
| Entity Tax Identification Number | 04-2995419 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 33 Broad Street |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02109 |
| City Area Code | 617 |
| Local Phone Number | 263-6400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | HYB |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
