NET INCOME (LOSS) PER COMMON SHARE - Schedule of Net Income (Loss) per Share Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Earnings Per Share [Abstract]
Net income (loss)	$ 60,371	$ (8,833)	$ 190,676	$ 456,341
Net income (loss) attributable to noncontrolling interests	3,272	650	9,353	2,932
Net income (loss) attributable to Annaly	57,099	(9,483)	181,323	453,409
Dividends on preferred stock	37,260	37,158	74,417	74,219
Net income (loss) available (related) to common stockholders	$ 19,839	$ (46,641)	$ 106,906	$ 379,190
Weighted average shares of common stock outstanding-basic (in shares)	620,208,712	500,950,563	603,770,531	500,781,701
Add: Effect of stock awards, if dilutive (in shares)	894,506	0	1,111,764	633,814
Weighted average shares of common stock outstanding-diluted (in shares)	621,103,218	500,950,563	604,882,295	501,415,515
Net income (loss) per share available (related) to common share
Basic (in dollars per share)	$ 0.03	$ (0.09)	$ 0.18	$ 0.76
Diluted (in dollars per share)	$ 0.03	$ (0.09)	$ 0.18	$ 0.76