Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Interest rate swaps
Derivative [Line Items]
Average Monthly Notional	$ 5,369,996	$ 4,309,089
TBA securities
Derivative [Line Items]
Average Monthly Notional	538,338	603,206
Credit default swaps
Derivative [Line Items]
Average Monthly Notional	811,654	497,857
Futures
Derivative [Line Items]
Average Monthly Notional	319,250	246,669
Forwards
Derivative [Line Items]
Average Monthly Notional	23,200	15,567
Warrants
Derivative [Line Items]
Average Monthly Notional	177	1,926
Total return swaps
Derivative [Line Items]
Average Monthly Notional	$ 1,388	$ 875