Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Interest rate swaps
Derivative [Line Items]
Average Monthly Notional	$ 986,719	$ 1,009,110
TBA securities
Derivative [Line Items]
Average Monthly Notional	1,036,552	713,634
Credit default swaps
Derivative [Line Items]
Average Monthly Notional	168,088	277,990
Total return swaps
Derivative [Line Items]
Average Monthly Notional	4,590	6,975
Futures
Derivative [Line Items]
Average Monthly Notional	180,400	149,538
Options
Derivative [Line Items]
Average Monthly Notional	4,286	1,500
Forwards
Derivative [Line Items]
Average Monthly Notional	24,878	26,413
Warrants
Derivative [Line Items]
Average Monthly Notional	$ 1,897	$ 1,570