Financial Derivatives (Schedule of Gains and Losses on Derivative Contracts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	$ 15,438	$ 5,791
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(11,960)	(31,238)
Realized gains (losses) on financial derivatives, net	3,478	(25,447)
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	(4,427)	3,452
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	34,792	(684)
Unrealized gains (losses) on financial derivatives, net	30,365	2,768
Derivative [Member]
Derivative [Line Items]
Foreign currency translation		5
Interest rate swaps | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	15,438	5,791
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(8,653)	(31,075)
Realized gains (losses) on financial derivatives, net	6,785	(25,284)
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	(4,427)	3,452
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	23,890	13,173
Unrealized gains (losses) on financial derivatives, net	19,463	16,625
Credit default swaps on asset-backed indices | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(200)	(275)
Realized gains (losses) on financial derivatives, net	(200)	(275)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(1,370)	2,158
Unrealized gains (losses) on financial derivatives, net	(1,370)	2,158
Credit default swaps on corporate bond indices | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(4,567)	(1,348)
Realized gains (losses) on financial derivatives, net	(4,567)	(1,348)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	1,676	207
Unrealized gains (losses) on financial derivatives, net	1,676	207
Credit default swaps on corporate bonds | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(7)	(41)
Realized gains (losses) on financial derivatives, net	(7)	(41)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	62	(19)
Unrealized gains (losses) on financial derivatives, net	62	(19)
Total return swaps | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	20
Realized gains (losses) on financial derivatives, net	20
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(1)
Unrealized gains (losses) on financial derivatives, net	(1)
TBA securities | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	817	4,292
Realized gains (losses) on financial derivatives, net	817	4,292
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	3,948	(10,077)
Unrealized gains (losses) on financial derivatives, net	3,948	(10,077)
Futures | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		(2,933)
Realized gains (losses) on financial derivatives, net		(2,933)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		(5,664)
Unrealized gains (losses) on financial derivatives, net		(5,664)
Futures | Interest Rate Risk
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	434
Realized gains (losses) on financial derivatives, net	434
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	6,918
Unrealized gains (losses) on financial derivatives, net	6,918
Forwards | Currency risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	110	141
Realized gains (losses) on financial derivatives, net	110	141
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	395	(382)
Unrealized gains (losses) on financial derivatives, net	395	(382)
Warrants | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	86
Realized gains (losses) on financial derivatives, net	86
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(726)
Unrealized gains (losses) on financial derivatives, net	$ (726)
Warrants | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		0
Realized gains (losses) on financial derivatives, net		0
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		(80)
Unrealized gains (losses) on financial derivatives, net		(80)
Credit default swaps on asset-backed securities | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		1
Realized gains (losses) on financial derivatives, net		1
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		0
Unrealized gains (losses) on financial derivatives, net		$ 0