Segment Information - Components of Corporate/Other (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Interest income	$ 707,854	$ 574,926	$ 571,916
Interest expense	(552,400)	(426,749)	(448,005)
Net Interest Income	155,454	148,177	123,911
Investment fair value changes, net	(175,558)	128,049	(588,438)
Other income, net	21,204	12,018	4,188
Realized gains, net	5,334	17,993	30,424
Total non-interest (loss) income, net	(162,679)	393,804	(475,354)
General and administrative expenses	(140,908)	(165,218)	(113,498)
Portfolio Management Costs	(7,951)	(5,758)	(4,204)
Loan acquisition costs	(11,766)	(16,219)	(8,525)
Other expenses	(15,590)	(16,695)	(108,785)
Benefit from (Provision for) income taxes	19,920	(18,478)	4,608
Net (Loss) Income	(163,520)	319,613	(581,847)
Corporate/ Other
Segment Reporting Information [Line Items]
Interest income	6,844	4,746	9,136
Interest expense	(56,470)	(40,921)	(47,620)
Net Interest Income	(49,626)	(36,175)	(38,484)
Investment fair value changes, net	15,590	(1,565)	(2,004)
Other income, net	(901)	951	2,685
Realized gains, net	2,160	0	25,182
Total non-interest (loss) income, net	16,849	(614)	25,863
General and administrative expenses	(55,749)	(77,066)	(52,900)
Portfolio Management Costs	0	0	0
Loan acquisition costs	0	(4)	(10)
Other expenses	0	17	(718)
Benefit from (Provision for) income taxes	0	19,283	0
Net (Loss) Income	(88,526)	(94,559)	(66,249)
Corporate/ Other | Legacy Consolidated VIEs
Segment Reporting Information [Line Items]
Interest income	5,672	4,709	9,061
Interest expense	(5,206)	(3,040)	(5,945)
Net Interest Income	466	1,669	3,116
Investment fair value changes, net	(1,302)	(1,558)	(1,512)
Other income, net	0	0	0
Realized gains, net	0	0	0
Total non-interest (loss) income, net	(1,302)	(1,558)	(1,512)
General and administrative expenses	0	0	0
Portfolio Management Costs	0	0	0
Loan acquisition costs	0	0	0
Other expenses	0	0	0
Benefit from (Provision for) income taxes	0	0	0
Net (Loss) Income	(836)	111	1,604
Corporate/ Other | Other
Segment Reporting Information [Line Items]
Interest income	1,172	37	75
Interest expense	(51,264)	(37,881)	(41,675)
Net Interest Income	(50,092)	(37,844)	(41,600)
Investment fair value changes, net	16,892	(7)	(492)
Other income, net	(901)	951	2,685
Realized gains, net	2,160	0	25,182
Total non-interest (loss) income, net	18,151	944	27,375
General and administrative expenses	(55,749)	(77,066)	(52,900)
Portfolio Management Costs	0	0	0
Loan acquisition costs	0	(4)	(10)
Other expenses	0	17	(718)
Benefit from (Provision for) income taxes	0	19,283	0
Net (Loss) Income	$ (87,690)	$ (94,670)	$ (67,853)