| Cover | Mar. 26, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 26, 2024 |
| Current Fiscal Year End Date | --09-30 |
| Entity File Number | 001-40135 |
| Entity Registrant Name | NORTHERN STAR INVESTMENT CORP. IV |
| Entity Central Index Key | 0001835814 |
| Entity Tax Identification Number | 85-3156787 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | The Chrysler Building |
| Entity Address, Address Line Two | 405 Lexington Avenue |
| Entity Address, Address Line Three | 44th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10174 |
| City Area Code | 212 |
| Local Phone Number | 818-8800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
