NET INCOME (LOSS) PER COMMON SHARE - Schedule of Net Income (Loss) per Share Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Net income (loss)	$ 82,351	$ (569,084)	$ 538,692	$ (1,247,225)
Net income (loss) attributable to noncontrolling interests	15,906	(6,879)	18,838	(7,797)
Net income (loss) attributable to Annaly	66,445	(562,205)	519,854	(1,239,428)
Dividends on preferred stock	41,628	36,854	115,847	104,495
Net income (loss) available (related) to common stockholders	$ 24,817	$ (599,059)	$ 404,007	$ (1,343,923)
Weighted average shares of common stock outstanding-basic (in shares)	515,729,658	494,330,361	505,800,723	492,744,997
Add: Effect of stock awards, if dilutive (in shares)	1,102,494	0	817,420	0
Weighted average shares of common stock outstanding-diluted (in shares)	516,832,152	494,330,361	506,618,143	492,744,997
Net income (loss) per share available (related) to common share
Basic (in dollars per share)	$ 0.05	$ (1.21)	$ 0.80	$ (2.73)
Diluted (in dollars per share)	$ 0.05	$ (1.21)	$ 0.80	$ (2.73)