Derivative Instruments - Activity of Derivative Instruments Not Designated as Hedges (Details) - Trading - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Interest rate caps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	$ 45,142	$ 45,142
Additions/ Transfers In	45,142	45,142
Terminations/Pair-Offs	(45,142)	(45,142)
Ending balance	45,142	45,142
Options
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	0	0
Additions/ Transfers In	190	160
Terminations/Pair-Offs	(190)	0
Ending balance	0	160
TBAs
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	0
Additions/ Transfers In	450,000
Terminations/Pair-Offs	(300,000)
Ending balance	150,000
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	4,919,398	4,134,267
Additions/ Transfers In	340,635	1,584,169
Terminations/Pair-Offs	(507,940)	(1,224,060)
Ending balance	4,752,093	4,494,376
Credit default swaps
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	475,000	400,000
Additions/ Transfers In	150,000	0
Terminations/Pair-Offs	(475,000)	0
Ending balance	150,000	400,000
U.S. Treasury futures
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	901,200	406,100
Additions/ Transfers In	2,984,000	112,500
Terminations/Pair-Offs	(2,073,000)	(406,100)
Ending balance	1,812,200	$ 112,500
Commodity futures
Derivative Instruments and Hedging Activities Disclosures [Roll Forward]
Beginning balance	199,676
Additions/ Transfers In	635,411
Terminations/Pair-Offs	(835,087)
Ending balance	$ 0