SEGMENTS - Schedule of Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	[1]
Segment Reporting Information [Line Items]
Interest income	$ 1,229,341	$ 1,001,485	$ 3,501,154	$ 2,741,229
Interest expense	1,215,940	1,046,819	3,440,646	2,799,063
Net interest income	13,401	(45,334)	60,508	(57,834)
Servicing and related income	122,583	97,620	358,182	265,683
Servicing and related expense	12,988	9,623	37,821	26,433
Net servicing income	109,595	87,997	320,361	239,250
Other income (loss)	(2,859)	(559,446)	290,058	(1,267,287)
Less: Total general and administrative expenses	43,921	39,909	127,382	123,652
Income (loss) before income taxes	76,216	(556,692)	543,545	(1,209,523)
Income taxes	(6,135)	12,392	4,853	37,702
Net income (loss)	82,351	(569,084)	538,692	(1,247,225)
Less: Net income (loss) attributable to noncontrolling interest	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)
Unrealized gains (losses) on available-for-sale securities	428,955	(825,286)	92,843	(443,957)
Reclassification adjustment for net (gains) losses included in net income (loss)	15,769	513,041	530,354	1,458,077
Other comprehensive income (loss)	444,724	(312,245)	623,197	1,014,120
Comprehensive income (loss)	527,075	(881,329)	1,161,889	(233,105)
Comprehensive income (loss) attributable to noncontrolling interests	15,906	(6,879)	18,838	(7,797)
Comprehensive income (loss) attributable to Annaly	511,169	(874,450)	1,143,051	(225,308)
Receivable for unsettled trades	766,341	1,047,566	766,341	1,047,566	$ 2,710,224
Payable for unsettled trades	1,885,286	2,214,319	1,885,286	2,214,319	3,249,389
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	444,724	(312,245)	623,197	1,014,120
Dividends declared, not yet paid	362,731	321,629	362,731	321,629	325,052
Total assets	101,515,995	89,648,423	101,515,995	89,648,423	$ 93,227,236
Operating Segments | Agency
Segment Reporting Information [Line Items]
Interest income	830,407	756,479	2,433,672	2,058,371
Interest expense	885,982	849,422	2,563,077	2,279,586
Net interest income	(55,575)	(92,943)	(129,405)	(221,215)
Servicing and related income	0	0	0	0
Servicing and related expense	0	0	0	0
Net servicing income	0	0	0	0
Other income (loss)	(6,658)	(528,640)	109,384	(1,415,438)
Less: Total general and administrative expenses	16,154	14,576	47,604	44,401
Income (loss) before income taxes	(78,387)	(636,159)	(67,625)	(1,681,054)
Income taxes	23	727	748	1,213
Net income (loss)	(78,410)	(636,886)	(68,373)	(1,682,267)
Less: Net income (loss) attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to Annaly	(78,410)	(636,886)	(68,373)	(1,682,267)
Dividends on preferred stock	0	0	0	0
Net income (loss) available (related) to common stockholders	(78,410)	(636,886)	(68,373)	(1,682,267)
Unrealized gains (losses) on available-for-sale securities	428,955	(825,286)	92,843	(443,957)
Reclassification adjustment for net (gains) losses included in net income (loss)	15,769	513,041	530,354	1,458,077
Other comprehensive income (loss)	444,724	(312,245)	623,197	1,014,120
Comprehensive income (loss)	366,314	(949,131)	554,824	(668,147)
Comprehensive income (loss) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Annaly	366,314	(949,131)	554,824	(668,147)
Receivable for unsettled trades	727,124	1,039,173	727,124	1,039,173
Payable for unsettled trades	1,811,196	2,144,692	1,811,196	2,144,692
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	444,724	(312,245)	623,197	1,014,120
Dividends declared, not yet paid	0	0	0	0
Total assets	71,699,019	70,047,768	71,699,019	70,047,768
Operating Segments | Resi-credit
Segment Reporting Information [Line Items]
Interest income	396,694	239,194	1,059,247	658,849
Interest expense	328,440	193,271	872,118	504,011
Net interest income	68,254	45,923	187,129	154,838
Servicing and related income	0	0	0	0
Servicing and related expense	0	0	0	0
Net servicing income	0	0	0	0
Other income (loss)	36,028	(12,974)	189,851	91,439
Less: Total general and administrative expenses	13,868	12,195	39,690	36,757
Income (loss) before income taxes	90,414	20,754	337,290	209,520
Income taxes	(8,263)	5,985	(9,966)	14,034
Net income (loss)	98,677	14,769	347,256	195,486
Less: Net income (loss) attributable to noncontrolling interest	15,906	(6,879)	18,838	(7,797)
Net income (loss) attributable to Annaly	82,771	21,648	328,418	203,283
Dividends on preferred stock	0	0	0	0
Net income (loss) available (related) to common stockholders	82,771	21,648	328,418	203,283
Unrealized gains (losses) on available-for-sale securities	0	0	0	0
Reclassification adjustment for net (gains) losses included in net income (loss)	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Comprehensive income (loss)	98,677	14,769	347,256	195,486
Comprehensive income (loss) attributable to noncontrolling interests	15,906	(6,879)	18,838	(7,797)
Comprehensive income (loss) attributable to Annaly	82,771	21,648	328,418	203,283
Receivable for unsettled trades	0	0	0	0
Payable for unsettled trades	0	1,546	0	1,546
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	0	0	0	0
Dividends declared, not yet paid	0	0	0	0
Total assets	26,235,097	16,616,765	26,235,097	16,616,765
Operating Segments | MSR
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Interest expense	0	0	0	0
Net interest income	0	0	0	0
Servicing and related income	122,583	97,620	358,182	265,683
Servicing and related expense	12,988	9,623	37,821	26,433
Net servicing income	109,595	87,997	320,361	239,250
Other income (loss)	(33,967)	(21,870)	(12,513)	61,314
Less: Total general and administrative expenses	8,876	7,657	25,977	22,210
Income (loss) before income taxes	66,752	58,470	281,871	278,354
Income taxes	2,126	5,858	14,195	22,706
Net income (loss)	64,626	52,612	267,676	255,648
Less: Net income (loss) attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to Annaly	64,626	52,612	267,676	255,648
Dividends on preferred stock	0	0	0	0
Net income (loss) available (related) to common stockholders	64,626	52,612	267,676	255,648
Unrealized gains (losses) on available-for-sale securities	0	0	0	0
Reclassification adjustment for net (gains) losses included in net income (loss)	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Comprehensive income (loss)	64,626	52,612	267,676	255,648
Comprehensive income (loss) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Annaly	64,626	52,612	267,676	255,648
Receivable for unsettled trades	39,217	8,393	39,217	8,393
Payable for unsettled trades	74,090	38,231	74,090	38,231
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	0	0	0	0
Dividends declared, not yet paid	0	0	0	0
Total assets	3,371,113	2,647,052	3,371,113	2,647,052
Corporate & Other
Segment Reporting Information [Line Items]
Interest income	2,240	5,812	8,235	24,009
Interest expense	1,518	4,126	5,451	15,466
Net interest income	722	1,686	2,784	8,543
Servicing and related income	0	0	0	0
Servicing and related expense	0	0	0	0
Net servicing income	0	0	0	0
Other income (loss)	1,738	4,038	3,336	(4,602)
Less: Total general and administrative expenses	5,023	5,481	14,111	20,284
Income (loss) before income taxes	(2,563)	243	(7,991)	(16,343)
Income taxes	(21)	(178)	(124)	(251)
Net income (loss)	(2,542)	421	(7,867)	(16,092)
Less: Net income (loss) attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to Annaly	(2,542)	421	(7,867)	(16,092)
Dividends on preferred stock	41,628	36,854	115,847	104,495
Net income (loss) available (related) to common stockholders	(44,170)	(36,433)	(123,714)	(120,587)
Unrealized gains (losses) on available-for-sale securities	0	0	0	0
Reclassification adjustment for net (gains) losses included in net income (loss)	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Comprehensive income (loss)	(2,542)	421	(7,867)	(16,092)
Comprehensive income (loss) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Annaly	(2,542)	421	(7,867)	(16,092)
Receivable for unsettled trades	0	0	0	0
Payable for unsettled trades	0	29,850	0	29,850
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	0	0	0	0
Dividends declared, not yet paid	362,731	321,629	362,731	321,629
Total assets	$ 210,766	$ 336,838	$ 210,766	$ 336,838

[1] (1)Derived from the audited consolidated financial statements at December 31, 2023.