| Document and Entity Information | Oct. 01, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 01, 2024 |
| Entity Registrant Name | BLACKROCK FINANCE, INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-33099 |
| Entity Tax Identification Number | 32-0174431 |
| Entity Address Address Line 1 | 50 Hudson Yards |
| Entity Address City Or Town | New York |
| Entity Address State Or Province | NY |
| Entity Address Postal Zip Code | 10001 |
| City Area Code | 212 |
| Local Phone Number | 810-5800 |
| Entity Information Former Legal Or Registered Name | BlackRock, Inc. |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | 1.250% Notes due 2025 |
| Trading Symbol | BLK25 |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Current Fiscal Year End Date | --12-31 |
| Entity Central Index Key | 0001364742 |
| Amendment Flag | false |
