| Document and Entity Information | Oct. 31, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 31, 2024 |
| Entity File Number | 001-06155 |
| Entity Registrant Name | ONEMAIN FINANCE CORPORATION |
| Entity Central Index Key | 0000025598 |
| Entity Incorporation, State or Country Code | IN |
| Entity Tax Identification Number | 35-0416090 |
| Entity Address, Address Line One | 601 N.W. Second Street |
| Entity Address, City or Town | Evansville |
| Entity Address, State or Province | IN |
| Entity Address, Postal Zip Code | 47708 |
| City Area Code | 812 |
| Local Phone Number | 424-8031 |
| Entity Emerging Growth Company | false |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
