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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net income (loss)	$ (273,977)	$ 521,534	$ 2,613,234	$ 1,977,820
Net income (loss) attributable to noncontrolling interests	1,287	2,290	(453)	3,405
Net income (loss) attributable to Annaly	(275,264)	519,244	2,613,687	1,974,415
Dividends on preferred stock	26,883	26,883	80,649	80,649
Net income (loss) available (related) to common stockholders	$ (302,147)	$ 492,361	$ 2,533,038	$ 1,893,766
Weighted average shares of common stock outstanding-basic (in shares)	429,858,876	361,328,979	392,172,655	354,606,052
Add: Effect of stock awards, if dilutive (in shares)	0	260,488	272,379	269,499
Weighted average shares of common stock outstanding-diluted (in shares)	429,858,876	361,589,467	392,445,034	354,875,551
Net income (loss) per share available (related) to common share
Basic (in dollars per share)	$ (0.70)	$ 1.36	$ 6.46	$ 5.34
Diluted (in dollars per share)	$ (0.70)	$ 1.36	$ 6.45	$ 5.34