Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021
Interest rate swaps
Derivative [Line Items]
Average Monthly Notional	$ 1,009,110	$ 1,343,094
TBA securities
Derivative [Line Items]
Average Monthly Notional	713,634	1,105,311
Credit default swaps
Derivative [Line Items]
Average Monthly Notional	277,990	110,084
Total return swaps
Derivative [Line Items]
Average Monthly Notional	6,975	2,593
Futures
Derivative [Line Items]
Average Monthly Notional	149,538	193,600
Options
Derivative [Line Items]
Average Monthly Notional	1,500	13,846
Forwards
Derivative [Line Items]
Average Monthly Notional	26,413	21,188
Warrants
Derivative [Line Items]
Average Monthly Notional	$ 1,570	$ 1,948