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Residential Whole Loans - Allowance for Credit Losses (Details) - Residential whole loans - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 10,194	$ 10,665	$ 19,612	$ 20,451	$ 10,665
Current provision/(reversal)	791	145	(1,079)	(460)
Write-offs	(1,036)	(616)	(5,262)	(379)
Ending balance	9,949	10,194	13,271	19,612	9,949
Non-QM loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	4,845,752				4,845,752	$ 4,291,086
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,928	2,125	1,681	1,871	2,125
Current provision/(reversal)	87	(197)	(326)	(190)
Write-offs	0	0	0	0
Ending balance	2,015	1,928	1,355	1,681	2,015
Business purpose loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	2,898,559				2,898,559	3,396,181
Business purpose loans \| Single-family rental loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,292,584				1,292,584	1,356,400
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	980	366	4,642	4,355	366
Current provision/(reversal)	(43)	614	978	228
Write-offs	0	0	(5,011)
Write-offs				59
Ending balance	937	980	609	4,642	937
Business purpose loans \| Single-family transitional loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	875,201				875,201	1,100,855
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	865	1,389	1,699	2,587	1,389
Current provision/(reversal)	669	(88)	(317)	(472)
Write-offs	(1,022)	(436)	(81)	(416)
Ending balance	512	865	1,301	1,699	512
Business purpose loans \| Single-family transitional loans \| Collateral Dependent Methodology
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	5,200		20,400		5,200
Legacy RPL/NPL loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,033,705				1,033,705	$ 1,082,549
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,421	6,785	11,590	11,638	6,785
Current provision/(reversal)	78	(184)	(1,414)	(26)
Write-offs	(14)	(180)	(170)	(22)
Ending balance	6,485	$ 6,421	10,006	$ 11,590	6,485
Legacy RPL/NPL loans \| Collateral Dependent Methodology
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 31,800		$ 44,400		$ 31,800