CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Total stockholder’s equity	Preferred stock	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit		Accumulated deficit Cumulative effect of change in accounting principle for credit losses	Accumulated deficit Beginning of period - adjusted	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]
Issuance						0	(93)
Buyback of common stock						(277)	(174,799)
Stock-based award activity						3	4,928
Direct purchase and dividend reinvestment						2	1,073
Unrealized gains (losses) on available-for-sale securities		$ 2,220,271						2,220,271
Reclassification adjustment for net gains (losses) included in net income (loss)		(769,406)						(769,406)
Net income (loss) attributable to Annaly		(1,768,379)							(1,768,379)
Dividends declared on preferred stock	[1]								(106,527)
Dividends and dividend equivalents declared on common stock and share-based awards		(976,966)							(976,966)	[1]
Net income (loss) attributable to noncontrolling interests		28											(28)
Equity contributions from (distributions to) noncontrolling interests													8,167
End of period at Sep. 30, 2020		14,194,672		$ 14,182,206	1,982,026	14,029	19,798,032	3,589,056	(11,200,937)				12,466
Beginning of period at Jun. 30, 2020					1,982,026	14,077	19,827,216	3,842,074	(11,871,927)		0	(11,871,927)	4,137
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance						0	0
Buyback of common stock						(49)	(31,363)
Stock-based award activity						0	1,510
Direct purchase and dividend reinvestment						1	669
Unrealized gains (losses) on available-for-sale securities		(140,671)						(140,671)
Reclassification adjustment for net gains (losses) included in net income (loss)		(112,347)						(112,347)
Net income (loss) attributable to Annaly		1,015,674							1,015,674
Dividends declared on preferred stock	[1]								(35,509)
Dividends and dividend equivalents declared on common stock and share-based awards		(309,175)							(309,175)	[1]
Net income (loss) attributable to noncontrolling interests		126											(126)
Equity contributions from (distributions to) noncontrolling interests													8,455
End of period at Sep. 30, 2020		14,194,672		14,182,206	1,982,026	14,029	19,798,032	3,589,056	(11,200,937)				12,466
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]
Issuance						511	468,823
Buyback of common stock						0	0
Stock-based award activity						6	8,725
Direct purchase and dividend reinvestment						0	0
Unrealized gains (losses) on available-for-sale securities		(1,733,919)						(1,733,919)
Reclassification adjustment for net gains (losses) included in net income (loss)		(1,778)						(1,778)
Net income (loss) attributable to Annaly		1,974,415							1,974,415
Dividends declared on preferred stock	[1]								(80,649)
Dividends and dividend equivalents declared on common stock and share-based awards		(946,648)							(946,648)	[1]
Net income (loss) attributable to noncontrolling interests		(3,405)											3,405
Equity contributions from (distributions to) noncontrolling interests													3,180
End of period at Sep. 30, 2021		13,717,867		13,697,802	1,536,569	14,499	20,228,366	1,638,638	(9,720,270)				20,065
Beginning of period at Jun. 30, 2021					1,536,569	14,442	20,178,692	1,780,275	(9,892,863)		$ 0	$ (9,892,863)	22,061
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance						55	48,853
Buyback of common stock						0	0
Stock-based award activity						2	821
Direct purchase and dividend reinvestment						0	0
Unrealized gains (losses) on available-for-sale securities		(113,451)						(113,451)
Reclassification adjustment for net gains (losses) included in net income (loss)		(28,186)						(28,186)
Net income (loss) attributable to Annaly		519,244							519,244
Dividends declared on preferred stock	[1]								(26,883)
Dividends and dividend equivalents declared on common stock and share-based awards		(319,768)							(319,768)	[1]
Net income (loss) attributable to noncontrolling interests		(2,290)											2,290
Equity contributions from (distributions to) noncontrolling interests													(4,286)
End of period at Sep. 30, 2021		$ 13,717,867		$ 13,697,802	$ 1,536,569	$ 14,499	$ 20,228,366	$ 1,638,638	$ (9,720,270)				$ 20,065

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

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