CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Preferred stock	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit		Accumulated deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated deficit Cumulative Effect, Period of Adoption, Adjusted Balance	Total stockholder’s equity	Noncontrolling interests
Beginning of period at Dec. 31, 2019				$ 1,982,026	$ 14,301	$ 19,966,923	$ 2,138,191	$ (8,309,424)		$ (39,641)	$ (8,349,065)		$ 4,327
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based award activity					3	1,449
Unrealized gains (losses) on available-for-sale securities		$ 1,374,796					1,374,796
Reclassification adjustment for net gains (losses) included in net income (loss)		(391,616)					(391,616)
Net income (loss) attributable to Annaly		(3,640,255)						(3,640,255)
Dividends declared on preferred stock	[1]							(35,509)
Dividends and dividend equivalents declared on common stock and share-based awards		(357,819)						(357,819)	[1]
Net income (loss) attributable to noncontrolling interests		(66)											66
Equity contributions from (distributions to) noncontrolling interests													(288)
End of period at Mar. 31, 2020		12,707,530		1,982,026	14,304	19,968,372	3,121,371	(12,382,648)				$ 12,703,425	4,105
Beginning of period at Dec. 31, 2020		14,021,796	[2]	1,536,569	13,982	19,750,818	3,374,335	(10,667,388)		$ 0	$ (10,667,388)		13,480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based award activity					3	4,008
Unrealized gains (losses) on available-for-sale securities		(1,428,927)					(1,428,927)
Reclassification adjustment for net gains (losses) included in net income (loss)		56,823					56,823
Net income (loss) attributable to Annaly		1,750,813						1,750,813
Dividends declared on preferred stock	[1]							(26,883)
Dividends and dividend equivalents declared on common stock and share-based awards		(308,346)						(308,346)	[1]
Net income (loss) attributable to noncontrolling interests		(321)											321
Equity contributions from (distributions to) noncontrolling interests													(2,013)
End of period at Mar. 31, 2021		$ 14,067,595		$ 1,536,569	$ 13,985	$ 19,754,826	$ 2,002,231	$ (9,251,804)				$ 14,055,807	$ 11,788

[1] Refer to the “Capital Stock” Note for dividends per share for each class of shares.

[2] Derived from the audited consolidated financial statements at December 31, 2020.