| Cover | Oct. 31, 2022 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 31, 2022 |
| Entity Registrant Name | NEXTNAV INC. |
| Entity Central Index Key | 0001865631 |
| Entity File Number | 001-40985 |
| Entity Tax Identification Number | 87-0854654 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1775 Tysons Blvd., |
| Entity Address, Address Line Two | 5th Floor |
| Entity Address, City or Town | McLean |
| Entity Address, State or Province | VA |
| City Area Code | (800) |
| Local Phone Number | 775-0982 |
| Entity Address, Postal Zip Code | 22102 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Common Stock, par value $0.0001 per share | |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | NN |
| Security Exchange Name | NASDAQ |
| Warrants, each to purchase one share of Common Stock | |
| Title of 12(b) Security | Warrants, each to purchase one share of Common Stock |
| Trading Symbol | NNAVW |
| Security Exchange Name | NASDAQ |
