Investment Securities Available For Sale, at Fair Value - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Accrued interest	$ 11,000,000		$ 9,800,000
Unrealized (loss) gains on investment securities available for sale	$ (33,200,000)	$ 900,000
Contractual maturities (up to)	39 years
Weighted average life of available for sale securities portfolio	6 years		6 years 10 months 24 days
Non Agency RMBS Held In Securitization Trust | Non-Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Realized loss on write-downs	$ (400,000)	$ 0