SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Asset-Backed Commercial Paper Conduits (Details) - USD ($) $ in Millions |
6 Months Ended | 9 Months Ended | |
|---|---|---|---|
Jun. 30, 2026 |
Sep. 30, 2025 |
Dec. 31, 2025 |
|
| Classification of Other Securitization Details | |||
| Commercial paper | $ 27,647 | $ 19,941 | |
| Short-term borrowings, at fair value | 68,978 | 51,878 | |
| Municipal securities tender option bond trusts (TOBs) | |||
| Classification of Other Securitization Details | |||
| Short-term borrowings, at fair value | 3,500 | 2,900 | |
| Citi-administered asset-backed commercial paper conduits | |||
| Classification of Other Securitization Details | |||
| Purchased assets outstanding under conduits | 20,000 | 19,200 | |
| Incremental funding commitments with clients | $ 16,200 | 17,500 | |
| Weighted average life of commercial paper issued by conduits | 66 days | 58 days | |
| Citi-administered asset-backed consolidated commercial paper conduits (ABCP) | |||
| Classification of Other Securitization Details | |||
| Letters of credit provided to conduits | $ 2,000 | 2,000 | |
| Commercial paper | $ 8,200 | $ 9,200 |