Investment Securities - Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
RMBS, available-for-sale	$ 86,717	$ 88,283
Credit loss allowance	46,910	37,369
HTM debt securities	229,632	216,936
Equity security, fair value		628
Total investment securities	308,203	301,000
VIE eliminations
Debt Securities, Available-for-sale [Line Items]
Equity security	(1,597,627)	(1,657,029)
RMBS
Debt Securities, Available-for-sale [Line Items]
RMBS, available-for-sale	86,717	88,283
CMBS
Debt Securities, Available-for-sale [Line Items]
RMBS, available-for-sale	38,764	32,522
Credit loss allowance	7	13
HTM debt securities	90,130	92,629
Before consolidation of securitization VIEs
Debt Securities, Available-for-sale [Line Items]
HTM debt securities	182,722	179,567
Equity security, fair value	0	628
Total investment securities	1,905,830	1,958,029
Before consolidation of securitization VIEs \| RMBS
Debt Securities, Available-for-sale [Line Items]
RMBS, available-for-sale	86,717	88,283
Equity security	400,263	404,688
Before consolidation of securitization VIEs \| CMBS
Debt Securities, Available-for-sale [Line Items]
Equity security	1,236,128	1,284,863
Marketable securities, Non-controlling interest	$ 142,500	$ 146,500

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