Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Interest rate swaps
Derivative [Line Items]
Average Monthly Notional	$ 4,203,641	$ 3,292,243
TBA securities
Derivative [Line Items]
Average Monthly Notional	624,337	796,003
Credit default swaps
Derivative [Line Items]
Average Monthly Notional	433,155	130,819
Total return swaps
Derivative [Line Items]
Average Monthly Notional	599	688
Futures
Derivative [Line Items]
Average Monthly Notional	229,170	186,446
Options
Derivative [Line Items]
Average Monthly Notional	0	13,846
Forwards
Derivative [Line Items]
Average Monthly Notional	13,489	13,676
Warrants
Derivative [Line Items]
Average Monthly Notional	$ 2,371	$ 3,378