LOANS - Summary of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest income	$ 13,401	$ (45,334)	$ 60,508	$ (57,834)
Net income (loss) attributable to Annaly	66,445	(562,205)	519,854	(1,239,428)
Residential Mortgage Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest income	346,031	181,965	899,867	491,397
Net gains (losses) on disposal of investments	1,535	(1,087)	(1,810)	(3,358)
Net unrealized gains (losses) on instruments measured at fair value through earnings	558,161	(418,776)	469,462	(326,096)
Net income (loss) attributable to Annaly	$ 905,727	$ (237,898)	$ 1,367,519	$ 161,943