Summary of Significant Accounting Policies - Notes Payable (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2022 USD ($) subsidiary	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2020	Mar. 31, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Proceeds used to repurchase and retire securities		$ 2,054	$ 16,644	$ 12,153		$ 13,775
Series A Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Preferred stock, fixed-to-floating rate cumulative redeemable		7.25%	7.25%	7.25%	7.25%
Series B Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Preferred stock, fixed-to-floating rate cumulative redeemable		5.00%	5.00%	5.00%	5.00%
8.875% Senior Unsecured Notes Due September 2027 | Senior notes
Summary Of Significant Accounting Policies [Line Items]
Original Principal	$ 110,000
Interest Rate	8.875%
Debt instrument, term (in years)	5 years
Issuance amount, amount of par value (percent)	0.99009
Number of subsidiaries (the "Guarantors") | subsidiary	2
Proceeds from unsecured notes payable	$ 106,100
Proceeds used to repurchase and retire securities		$ 90,000
Amount Outstanding		$ 110,000	$ 110,000