| Cover | Mar. 12, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 12, 2024 |
| Entity File Number | 811-21432 |
| Entity Registrant Name | Reaves Utility Income Fund |
| Entity Central Index Key | 0001263994 |
| Entity Tax Identification Number | 20-0223928 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1700 Broadway |
| Entity Address, Address Line Two | Suite 1850 |
| Entity Address, City or Town | Denver |
| Entity Address, State or Province | CO |
| Entity Address, Postal Zip Code | 80290 |
| City Area Code | 800 |
| Local Phone Number | 644-5571 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares of Beneficial Interest |
| Trading Symbol | UTG |
| Security Exchange Name | NYSEAMER |
| Entity Emerging Growth Company | false |
