| Line Item | Jun 30, 2026 | Mar 31, 2026 | Dec 31, 2025 | Sep 30, 2025 | Jun 30, 2025 | Mar 31, 2025 | Dec 31, 2024 | Sep 30, 2024 | Jun 30, 2024 | Mar 31, 2024 | Dec 31, 2023 | Sep 30, 2023 | Jun 30, 2023 | Mar 31, 2023 | Dec 31, 2022 | Sep 30, 2022 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Net interest income | ||||||||||||||||
| Interest income | ||||||||||||||||
| Interest expense | ||||||||||||||||
| Net interest income | ||||||||||||||||
| Net servicing income | ||||||||||||||||
| Servicing and related income | ||||||||||||||||
| Servicing and related expense | ||||||||||||||||
| Net servicing income | ||||||||||||||||
| Other income (loss) | ||||||||||||||||
| Net gains (losses) on investments and other | ||||||||||||||||
| Net gains (losses) on derivatives | ||||||||||||||||
| Other, net | ||||||||||||||||
| Total other income (loss) | ||||||||||||||||
| General and administrative expenses | ||||||||||||||||
| Compensation expense | ||||||||||||||||
| Other general and administrative expenses | ||||||||||||||||
| Total general and administrative expenses | ||||||||||||||||
| Income (loss) before income taxes | ||||||||||||||||
| Income taxes | ||||||||||||||||
| Net income (loss) | ||||||||||||||||
| Net income (loss) attributable to noncontrolling interests | ||||||||||||||||
| Net income (loss) attributable to Annaly | ||||||||||||||||
| Dividends on preferred stock | ||||||||||||||||
| Net income (loss) available (related) to common stockholders | ||||||||||||||||
| Basic (in dollars per share) | ||||||||||||||||
| Diluted (in dollars per share) |