Investments - Narrative (Details)			3 Months Ended				6 Months Ended
		Jan. 01, 2023 USD ($)	Jun. 30, 2023 USD ($) joint_venture	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($) loan	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($) loan	Jun. 30, 2022 USD ($) loan	Dec. 31, 2022 USD ($)
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			$ (982,000)				$ (982,000)
Amortization of unrealized loss on debt securities available-for-sale transferred to held-to-maturity			1,139,000		$ 0		3,172,000	$ 0
Gross unrealized losses									$ (25,649,000)
Gross unrealized gains									0
Fair value									391,614,000
Interest receivable on securities, on available for sale debt securities			100,000				100,000		100,000
Debt securities and beneficial interests acquired					0
Basis	[1]		71,706,000				71,706,000		0
Securities past due			0				0		0
Impairment of beneficial interest			$ (8,800,000)	$ (1,000,000)	(2,100,000)	$ (4,000,000)
Number of joint ventures being refinanced | joint_venture			8
Beneficial interest, accretable yield			$ 2,000,000		2,500,000		4,100,000	6,600,000
Held-to-maturity securities, accretable yield			600,000				1,200,000
Reclassification to non-credit discount from the allowance for changes in payment expectations					$ 400,000			$ 800,000
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)	$ (7,770,000)				$ (7,770,000)		0
Ajax Mortgage Loan Trust 2022-A
Debt Securities, Available-for-sale [Line Items]
Securities retained, percentage from trust (in percent)			8.60%		23.30%		8.60%	23.30%
Securities retained, value					$ 49,200,000		$ 16,100,000	$ 49,200,000
Securities retained, number of re-performing loans and non-performing loans acquired | loan					811		1,085	811
Securities retained, re-performing loans and non-performing loans acquired, unpaid principal balance					$ 215,500,000		$ 205,100,000	$ 215,500,000
Securities retained, re-performing loans and non-performing loans acquired, amount					$ 518,800,000		$ 497,400,000	$ 518,800,000
Securities retained, rated securities with unpaid principal balance percentage (in percent)					71.90%		79.80%	71.90%
Securities retained, weighted average coupon (in percent)			3.46%		3.47%		3.46%	3.47%
Ajax Mortgage Loan Trust 2022-A | 60 Days Past Due
Debt Securities, Available-for-sale [Line Items]
Securities retained, percentage of unpaid loans (in percent)					33.90%			33.90%
Ajax Mortgage Loan Trust 2022-B
Debt Securities, Available-for-sale [Line Items]
Securities retained, percentage from trust (in percent)					17.20%			17.20%
Securities retained, value					$ 36,800,000			$ 36,800,000
Securities retained, number of re-performing loans and non-performing loans acquired | loan					1,106			1,106
Securities retained, re-performing loans and non-performing loans acquired, unpaid principal balance					$ 220,800,000			$ 220,800,000
Securities retained, re-performing loans and non-performing loans acquired, amount					$ 575,500,000			$ 575,500,000
Securities retained, rated securities with unpaid principal balance percentage (in percent)					76.90%			76.90%
Securities retained, weighted average coupon (in percent)					3.47%			3.47%
Investments in securities
Debt Securities, Available-for-sale [Line Items]
Fair value			$ 142,100,000				$ 142,100,000		257,100,000
Investment in beneficial interests
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses			(21,430,000)				(21,430,000)		0
Gross unrealized gains			0				0		0
Fair value			106,044,000				106,044,000		134,552,000
Reclassification to non-credit discount from the allowance for changes in payment expectations			0		$ 448,000		0	$ 759,000
Reversal of provision for credit losses					(400,000)			(100,000)
Senior notes
Debt Securities, Available-for-sale [Line Items]
Debt securities, realized loss			0		$ (100,000)		(3,000,000)	$ (100,000)
Debt securities available-for-sale, at fair value
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses			(11,760,000)				(11,760,000)		(25,649,000)
Gross unrealized gains			0				0		0
Fair value			$ 142,104,000				$ 142,104,000		$ 257,062,000

[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 June 30, 2023, Investments in securities HTM includes an allowance for expected credit losses of zero and remaining discount of $7.8 million related to the unamortized unrealized loss in AOCI.