Investments - Narrative (Details)			3 Months Ended
		Jan. 01, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($) loan	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Reclassification of available for sale debt securities to held to maturity		$ 83,000,000
Unrealized losses on debt securities available-for-sale transferred to held-to-maturity			$ (998,000)		$ (629,000)
Amortization of unrealized loss on debt securities available-for-sale transferred to held-to-maturity			795,000	$ 2,033,000
Gross unrealized losses					(8,700,000)
Gross unrealized gains					600,000
Interest receivable on securities, on available for sale debt securities			80,000		87,000
Basis	[1]		54,085,000		59,691,000
Securities past due			0		0
Beneficial interest, accretable yield			700,000	2,100,000
Held-to-maturity securities, accretable yield			400,000	600,000
Reclassification to non-credit discount from the allowance for changes in payment expectations			(900,000)	$ 0
Accumulated net investment gain (loss) attributable to parent
Debt Securities, Available-for-sale [Line Items]
Unrealized losses on debt securities available-for-sale transferred to held-to-maturity		$ (10,900,000)	(5,193,000)		(5,989,000)
Ajax Mortgage Loan Trust 2022-A
Debt Securities, Available-for-sale [Line Items]
Securities retained, percentage from trust (in percent)				8.60%
Ajax Mortgage Loan Trust 2023-A
Debt Securities, Available-for-sale [Line Items]
Securities retained, value				$ 16,100,000
Securities retained, re-performing loans and non-performing loans acquired, amount				$ 497,400,000
Securities retained, weighted average coupon (in percent)				3.46%
Securities retained, rated securities with unpaid principal balance percentage (in percent)				79.80%
Securities retained, number of re-performing loans and non-performing loans acquired | loan				1,085
Securities retained, re-performing loans and non-performing loans acquired, unpaid principal balance				$ 205,100,000
Securities retained, redemption, transaction costs				1,000,000
Investments in securities
Debt Securities, Available-for-sale [Line Items]
Fair value			125,100,000		131,600,000
Investment in beneficial interests
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses			(26,286,000)		(26,477,000)
Gross unrealized gains			5,148,000		3,631,000
Fair value			67,439,000		81,316,000
Reclassification to non-credit discount from the allowance for changes in payment expectations			(916,000)	0
Reversal of provision for credit losses			(3,100,000)
Senior notes
Debt Securities, Available-for-sale [Line Items]
Debt securities, realized loss			0	$ (3,000,000)
Debt securities available-for-sale, at fair value
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses			(8,809,000)		(8,675,000)
Gross unrealized gains			1,144,000		637,000
Fair value			$ 125,126,000		$ 131,558,000

[1] On January 1, 2023, the Company transferred certain of its investments in securities to held-to-maturity ("HTM") due to European risk retention regulations. As of March 31, 2024, Investments in securities HTM includes an allowance for expected credit losses of zero and remaining discount of $5.2 million related to the unamortized unrealized loss in Accumulated other comprehensive income ("AOCI"). As of December 31, 2023, Investments in securities HTM includes an allowance for expected credit losses of zero and remaining discount of $6.0 million related to the unamortized unrealized loss in AOCI.