Financial Derivatives (Schedule of Gains and Losses on Derivative Contracts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	$ 24,713	$ 4,514	$ (2,277)
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	15,337	115,975	13,796
Realized gains (losses) on financial derivatives, net	40,050	120,489	11,519
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	22,806	4,134	(763)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(37,854)	49,738	11,075
Unrealized gains (losses) on financial derivatives, net	(15,048)	53,872	10,312
Foreign currency transactions	(23)	150	(224)
Foreign currency translation	777	(882)	487
Derivative [Member]
Derivative [Line Items]
Foreign currency transactions	(4)		18
Foreign currency translation	12	(19)	(43)
Interest rate swaps | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps	24,713	4,514	(2,277)
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(1,037)	21,549	644
Realized gains (losses) on financial derivatives, net	23,676	26,063	(1,633)
Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps	22,806	4,134	(763)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(19,601)	46,989	12,051
Unrealized gains (losses) on financial derivatives, net	3,205	51,123	11,288
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		(855)	34
Realized gains (losses) on financial derivatives, net		(855)	34
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		615	(43)
Unrealized gains (losses) on financial derivatives, net		615	(43)
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	(1,332)	(277)	931
Realized gains (losses) on financial derivatives, net	(1,332)	(277)	931
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	1,873	982	(1,039)
Unrealized gains (losses) on financial derivatives, net	1,873	982	(1,039)
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	(4,891)	862	(330)
Realized gains (losses) on financial derivatives, net	(4,891)	862	(330)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(1,092)	(1,064)	(963)
Unrealized gains (losses) on financial derivatives, net	(1,092)	(1,064)	(963)
Credit default swaps on corporate bonds | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(55)	(284)	256
Realized gains (losses) on financial derivatives, net	(55)	(284)	256
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(29)	128	(345)
Unrealized gains (losses) on financial derivatives, net	(29)	128	(345)
Total return swaps | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps			(1,242)
Realized gains (losses) on financial derivatives, net			(1,242)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps			476
Unrealized gains (losses) on financial derivatives, net			476
Total return swaps | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	55
Realized gains (losses) on financial derivatives, net	55
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	6
Unrealized gains (losses) on financial derivatives, net	6
TBA securities | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	18,195	73,304	8,020
Realized gains (losses) on financial derivatives, net	18,195	73,304	8,020
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(9,616)	5,658	283
Unrealized gains (losses) on financial derivatives, net	(9,616)	5,658	283
Futures | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		20,586	4,656
Realized gains (losses) on financial derivatives, net		20,586	4,656
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		(4,848)	776
Unrealized gains (losses) on financial derivatives, net		(4,848)	776
Futures | Interest Rate/Currency Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	5,847
Realized gains (losses) on financial derivatives, net	5,847
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(10,421)
Unrealized gains (losses) on financial derivatives, net	(10,421)
Forwards | Currency risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(468)	1,045	1,183
Realized gains (losses) on financial derivatives, net	(468)	1,045	1,183
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	(136)	285	73
Unrealized gains (losses) on financial derivatives, net	(136)	285	73
Warrants | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps	(312)
Realized gains (losses) on financial derivatives, net	(312)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	566
Unrealized gains (losses) on financial derivatives, net	566
Warrants | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		(102)	0
Realized gains (losses) on financial derivatives, net		(102)	0
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		845	(46)
Unrealized gains (losses) on financial derivatives, net		845	(46)
Options | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps		147	(356)
Realized gains (losses) on financial derivatives, net		147	(356)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		148	(148)
Unrealized gains (losses) on financial derivatives, net		$ 148	$ (148)
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	(665)
Realized gains (losses) on financial derivatives, net	(665)
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps	596
Unrealized gains (losses) on financial derivatives, net	$ 596