LOANS - Summary of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest income	$ 273,200	$ 53,558	$ 493,171	$ 47,107
Net income (loss) attributable to Annaly	57,099	(9,483)	181,323	453,409
Residential Mortgage Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest income	467,959	301,820	894,014	553,836
Net gains (losses) on disposal of investments	(14,315)	(1,228)	(24,308)	(3,344)
Net unrealized gains (losses) on instruments measured at fair value through earnings	94,051	(3,913)	334,881	(88,698)
Net income (loss) attributable to Annaly	$ 547,695	$ 296,679	$ 1,204,587	$ 461,794