Derivative Instruments - Schedule of Activity of Derivative Instruments (Details) - Trading - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Interest rate caps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	$ 45,142	$ 45,142	$ 45,142	$ 45,142
Additions/ Long (Short)	26,500	0	71,642	45,142
Terminations/Pair-Offs	0	0	(45,142)	(45,142)
Ending balance	71,642	45,142	71,642	45,142
Options
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	0	0	0	0
Additions/ Long (Short)	2,801	0	2,801	0
Terminations/Pair-Offs	(1,900)	0	(1,900)	0
Ending balance	901	0	901	0
TBAs
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	650,000	10,000	0	0
Additions/ Long (Short)	650,000	130,000	2,800,000	150,000
Terminations/Pair-Offs	(3,150,000)	(110,000)	(4,650,000)	(120,000)
Ending balance	(1,850,000)	30,000	(1,850,000)	30,000
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	6,300,563	4,867,217	4,919,398	4,134,267
Additions/ Long (Short)	349,056	1,117,681	2,498,091	3,373,016
Terminations/Pair-Offs	0	(1,205,090)	(767,870)	(2,727,475)
Ending balance	6,649,619	4,779,808	6,649,619	4,779,808
Credit default swaps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	150,000	475,000	475,000	400,000
Additions/ Long (Short)	0	0	150,000	75,000
Terminations/Pair-Offs	0	0	(475,000)	0
Ending balance	150,000	475,000	150,000	475,000
U.S. Treasury futures
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	(886,500)	(247,500)	(901,200)	(406,100)
Additions/ Long (Short)	(7,687,100)	(1,051,700)	(11,894,500)	(1,521,100)
Terminations/Pair-Offs	4,589,900	673,500	8,812,000	1,301,500
Ending balance	(3,983,700)	(625,700)	(3,983,700)	(625,700)
Commodity futures
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	13,758	0	199,676	0
Additions/ Long (Short)	194,647	100,060	976,284	100,060
Terminations/Pair-Offs	(99,809)	0	(1,067,364)	0
Ending balance	108,596	$ 100,060	108,596	$ 100,060
Index futures
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance			0
Additions/ Long (Short)			384
Terminations/Pair-Offs			(384)
Ending balance	$ 0		$ 0