| Cover | Jan. 23, 2025 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 23, 2025 |
| Entity File Number | 811-22499 |
| Entity Registrant Name | NXG NextGen Infrastructure Income Fund |
| Entity Central Index Key | 0001506488 |
| Entity Tax Identification Number | 46-0742000 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | One Energy Square |
| Entity Address, Address Line Two | 4925 Greenville Avenue |
| Entity Address, Address Line Three | Suite 1310 |
| Entity Address, City or Town | Dallas |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75206 |
| City Area Code | (214) |
| Local Phone Number | 692-6334 |
| 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 | NXG |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
