| Cover | Jun. 03, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 17, 2024 |
| Entity Registrant Name | NEXTDECADE CORPORATION |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36842 |
| Entity Tax Identification Number | 46-5723951 |
| Entity Address, Address Line One | 1000 Louisiana Street |
| Entity Address, Address Line Two | Suite 3300 |
| Entity Address, City or Town | Houston |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77002 |
| City Area Code | 713 |
| Local Phone Number | 574-1880 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value |
| Trading Symbol | NEXT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001612720 |
