Financial Derivatives (Schedule of Gains and Losses on Derivative Contracts) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	$ 15,657	$ 23,555	$ 33,196	$ 49,744
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(23,992)	(65,119)	(30,409)	(81,518)
Realized gains (losses) on financial derivatives, net	(8,335)	(41,564)	2,787	(31,774)
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	(5,736)	(12,789)	(5,556)	(17,695)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	2,539	13,145	(50,364)	56,318
Unrealized gains (losses) on financial derivatives, net	(3,197)	356	(55,920)	38,623
Interest rate swaps | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	15,657	23,555	33,196	49,744
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(2,193)	(43,214)	(1,356)	(64,743)
Realized gains (losses) on financial derivatives, net	13,464	(19,659)	31,840	(14,999)
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	(5,736)	(12,789)	(5,556)	(17,695)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(7,332)	9,108	(45,869)	42,853
Unrealized gains (losses) on financial derivatives, net	(13,068)	(3,681)	(51,425)	25,158
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	(157)	0	(115)	(1,945)
Realized gains (losses) on financial derivatives, net	(157)	0	(115)	(1,945)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(219)	(2)	134	(49)
Unrealized gains (losses) on financial derivatives, net	(219)	(2)	134	(49)
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	(12,614)	(1,514)	(18,175)	(8,136)
Realized gains (losses) on financial derivatives, net	(12,614)	(1,514)	(18,175)	(8,136)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	7,499	1,133	1,258	2,639
Unrealized gains (losses) on financial derivatives, net	7,499	1,133	1,258	2,639
Credit default swaps on corporate bonds | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(33)	(1,886)	26	(23)
Realized gains (losses) on financial derivatives, net	(33)	(1,886)	26	(23)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	11	(870)	(74)	17
Unrealized gains (losses) on financial derivatives, net	11	(870)	(74)	17
Total return swaps | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	0		0
Realized gains (losses) on financial derivatives, net	0		0
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	13		13
Unrealized gains (losses) on financial derivatives, net	13		13
Total return swaps | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		(7)		33
Realized gains (losses) on financial derivatives, net		(7)		33
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		(26)		(6)
Unrealized gains (losses) on financial derivatives, net		(26)		(6)
Options | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(1,065)		(1,065)
Realized gains (losses) on financial derivatives, net	(1,065)		(1,065)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(1,479)		(5,311)
Unrealized gains (losses) on financial derivatives, net	(1,479)		(5,311)
TBA securities | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(2,759)	(4)	(2,973)	2,196
Realized gains (losses) on financial derivatives, net	(2,759)	(4)	(2,973)	2,196
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	138	(3)	(1,280)	4,284
Unrealized gains (losses) on financial derivatives, net	138	(3)	(1,280)	4,284
Futures | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(5,051)	(1,734)	(5,190)	(8,965)
Realized gains (losses) on financial derivatives, net	(5,051)	(1,734)	(5,190)	(8,965)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	3,583	(141)	1,034	7,516
Unrealized gains (losses) on financial derivatives, net	3,583	(141)	1,034	7,516
Forwards | Currency risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(120)	(16,308)	(1,561)	(20)
Realized gains (losses) on financial derivatives, net	(120)	(16,308)	(1,561)	(20)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	325	4,409	(261)	(208)
Unrealized gains (losses) on financial derivatives, net	325	4,409	(261)	(208)
Warrants | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		(452)	0	86
Realized gains (losses) on financial derivatives, net		(452)	0	86
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		(463)	(8)	(726)
Unrealized gains (losses) on financial derivatives, net		$ (463)	(8)	(726)
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	0		0
Realized gains (losses) on financial derivatives, net	0		0
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	0		0
Unrealized gains (losses) on financial derivatives, net	$ 0		$ 0
Credit Default Swap, 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				(2)
Unrealized gains (losses) on financial derivatives, net				$ (2)