Investment Securities - Purchases, Sales and Redemptions, and Principal Collections for All Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	$ 9,220	$ 591
Sales and redemptions	1,314	0
Principal collections	19,149	40,778
Securitization VIEs
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	0	0
Sales and redemptions	(3,166)	0
Principal collections	(15,022)	(15,329)
HTM Securities
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	9,220	591
Sales and redemptions	0
Principal collections	17,163	38,198
Equity Security
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	0	0
Sales and redemptions	1,314	0
Principal collections	0	0
RMBS \| Available-for-sale
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	0	0
Sales and redemptions	0	0
Principal collections	1,925	2,435
RMBS \| Fair value option
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	0	0
Sales and redemptions	0	0
Principal collections	11,883	14,220
CMBS \| Fair value option
Debt Securities, Available-for-sale [Line Items]
Purchases/fundings	0	0
Sales and redemptions	3,166	0
Principal collections	$ 3,200	$ 1,254