SEGMENTS - Schedule of Segment Reporting (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	[2]
Segment Reporting Information [Line Items]
Interest income		$ 1,532,497	$ 1,229,341	$ 4,268,498	$ 3,501,154
Interest expense		1,256,747	1,215,940	3,499,577	3,440,646
Net interest income		275,750	13,401	768,921	60,508
Servicing and related income		141,356	122,583	423,461	358,182
Servicing and related expense		15,104	12,988	43,788	37,821
Net servicing income		126,252	109,595	379,673	320,361
Other income (loss)		483,578	(2,859)	34,451	290,058
Less: Total general and administrative expenses		50,340	43,921	148,422	127,382
Income (loss) before income taxes		835,240	76,216	1,034,623	543,545
Income taxes		(7,823)	(6,135)	884	4,853
Net income (loss)		843,063	82,351	1,033,739	538,692
Less: Net income (loss) attributable to noncontrolling interest		10,618	15,906	19,971	18,838
Net income (loss) attributable to Annaly		832,445	66,445	1,013,768	519,854
Dividends on preferred stock	[1]	41,127	41,628	115,544	115,847
Net income (loss) available (related) to common stockholders		791,318	24,817	898,224	404,007
Unrealized gains (losses) on available-for-sale securities		113,281	428,955	311,717	92,843
Reclassification adjustment for net (gains) losses included in net income (loss)		2,378	15,769	81,578	530,354
Other comprehensive income (loss)		115,659	444,724	393,295	623,197
Comprehensive income (loss)		958,722	527,075	1,427,034	1,161,889
Comprehensive income (loss) attributable to noncontrolling interests		10,618	15,906	19,971	18,838
Comprehensive income (loss) attributable to Annaly		948,104	511,169	1,407,063	1,143,051
Receivable for unsettled trades		185,916	766,341	185,916	766,341	$ 2,201,447
Payable for unsettled trades		2,604,278	1,885,286	2,604,278	1,885,286	308,282
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment		115,659	444,724	393,295	623,197
Dividends declared, not yet paid		476,737	362,731	476,737	362,731	375,932
Total assets		125,861,572	101,515,995	125,861,572	101,515,995	$ 103,556,384
Operating Segments | Agency
Segment Reporting Information [Line Items]
Interest income		992,588	830,407	2,755,055	2,433,672
Interest expense		811,177	885,982	2,260,746	2,563,077
Net interest income		181,411	(55,575)	494,309	(129,405)
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)		495,445	(6,658)	75,668	109,384
Less: Total general and administrative expenses		17,827	16,154	51,694	47,604
Income (loss) before income taxes		659,029	(78,387)	518,283	(67,625)
Income taxes		(281)	23	(121)	748
Net income (loss)		659,310	(78,410)	518,404	(68,373)
Less: Net income (loss) attributable to noncontrolling interest		0	0	0	0
Net income (loss) attributable to Annaly		659,310	(78,410)	518,404	(68,373)
Dividends on preferred stock		0	0	0	0
Net income (loss) available (related) to common stockholders		659,310	(78,410)	518,404	(68,373)
Unrealized gains (losses) on available-for-sale securities		113,281	428,955	311,717	92,843
Reclassification adjustment for net (gains) losses included in net income (loss)		2,378	15,769	81,578	530,354
Other comprehensive income (loss)		115,659	444,724	393,295	623,197
Comprehensive income (loss)		774,969	366,314	911,699	554,824
Comprehensive income (loss) attributable to noncontrolling interests		0	0	0	0
Comprehensive income (loss) attributable to Annaly		774,969	366,314	911,699	554,824
Receivable for unsettled trades		179,767	727,124	179,767	727,124
Payable for unsettled trades		2,497,495	1,811,196	2,497,495	1,811,196
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment		115,659	444,724	393,295	623,197
Dividends declared, not yet paid		0	0	0	0
Total assets		85,802,242	71,699,019	85,802,242	71,699,019
Operating Segments | Resi-credit
Segment Reporting Information [Line Items]
Interest income		539,909	396,694	1,512,225	1,059,247
Interest expense		445,570	328,440	1,237,966	872,118
Net interest income		94,339	68,254	274,259	187,129
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)		32,343	36,028	44,240	189,851
Less: Total general and administrative expenses		16,755	13,868	48,178	39,690
Income (loss) before income taxes		109,927	90,414	270,321	337,290
Income taxes		(7,158)	(8,263)	(15,899)	(9,966)
Net income (loss)		117,085	98,677	286,220	347,256
Less: Net income (loss) attributable to noncontrolling interest		10,618	15,906	19,971	18,838
Net income (loss) attributable to Annaly		106,467	82,771	266,249	328,418
Dividends on preferred stock		0	0	0	0
Net income (loss) available (related) to common stockholders		106,467	82,771	266,249	328,418
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)		117,085	98,677	286,220	347,256
Comprehensive income (loss) attributable to noncontrolling interests		10,618	15,906	19,971	18,838
Comprehensive income (loss) attributable to Annaly		106,467	82,771	266,249	328,418
Receivable for unsettled trades		0	0	0	0
Payable for unsettled trades		22,067	0	22,067	0
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		35,811,143	26,235,097	35,811,143	26,235,097
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		141,356	122,583	423,461	358,182
Servicing and related expense		15,104	12,988	43,788	37,821
Net servicing income		126,252	109,595	379,673	320,361
Other income (loss)		(45,910)	(33,967)	(88,243)	(12,513)
Less: Total general and administrative expenses		9,423	8,876	28,059	25,977
Income (loss) before income taxes		70,919	66,752	263,371	281,871
Income taxes		(341)	2,126	17,002	14,195
Net income (loss)		71,260	64,626	246,369	267,676
Less: Net income (loss) attributable to noncontrolling interest		0	0	0	0
Net income (loss) attributable to Annaly		71,260	64,626	246,369	267,676
Dividends on preferred stock		0	0	0	0
Net income (loss) available (related) to common stockholders		71,260	64,626	246,369	267,676
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)		71,260	64,626	246,369	267,676
Comprehensive income (loss) attributable to noncontrolling interests		0	0	0	0
Comprehensive income (loss) attributable to Annaly		71,260	64,626	246,369	267,676
Receivable for unsettled trades		6,149	39,217	6,149	39,217
Payable for unsettled trades		84,716	74,090	84,716	74,090
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		4,147,960	3,371,113	4,147,960	3,371,113
Corporate & Other
Segment Reporting Information [Line Items]
Interest income		0	2,240	1,218	8,235
Interest expense		0	1,518	865	5,451
Net interest income		0	722	353	2,784
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)		1,700	1,738	2,786	3,336
Less: Total general and administrative expenses		6,335	5,023	20,491	14,111
Income (loss) before income taxes		(4,635)	(2,563)	(17,352)	(7,991)
Income taxes		(43)	(21)	(98)	(124)
Net income (loss)		(4,592)	(2,542)	(17,254)	(7,867)
Less: Net income (loss) attributable to noncontrolling interest		0	0	0	0
Net income (loss) attributable to Annaly		(4,592)	(2,542)	(17,254)	(7,867)
Dividends on preferred stock		41,127	41,628	115,544	115,847
Net income (loss) available (related) to common stockholders		(45,719)	(44,170)	(132,798)	(123,714)
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)		(4,592)	(2,542)	(17,254)	(7,867)
Comprehensive income (loss) attributable to noncontrolling interests		0	0	0	0
Comprehensive income (loss) attributable to Annaly		(4,592)	(2,542)	(17,254)	(7,867)
Receivable for unsettled trades		0	0	0	0
Payable for unsettled trades		0	0	0	0
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment		0	0	0	0
Dividends declared, not yet paid		476,737	362,731	476,737	362,731
Total assets		$ 100,227	$ 210,766	$ 100,227	$ 210,766

[1] (1) The three and nine months ended September 30, 2025 include cumulative and undeclared dividends of $3.7 million on the Company's 8.875% Series J Fixed-Rate Cumulative Redeemable Preferred Stock (the “Series J Preferred Stock”) as of September 30, 2025.

[2] (1)Derived from the audited consolidated financial statements at December 31, 2024.