Investment in Securities (Unrealized Loss Positions Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 556,772	$ 720,249
Unrealized Losses, Less than 12 Months	(24,527)	(60,343)
Fair Value, Greater than 12 Months	525,522	365,355
Unrealized Losses, Greater than 12 Months	(90,464)	(66,704)
Fair Value, Total	1,082,294	1,085,604
Unrealized Loss, Total	(114,991)	(127,047)
Agency RMBS
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	485,932	577,047
Unrealized Losses, Less than 12 Months	(21,140)	(51,817)
Fair Value, Greater than 12 Months	459,339	326,223
Unrealized Losses, Greater than 12 Months	(77,737)	(57,564)
Fair Value, Total	945,271	903,270
Unrealized Loss, Total	(98,877)	(109,381)
Non-Agency RMBS
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	3,062	46,644
Unrealized Losses, Less than 12 Months	(165)	(5,205)
Fair Value, Greater than 12 Months	42,113	26,194
Unrealized Losses, Greater than 12 Months	(7,532)	(4,959)
Fair Value, Total	45,175	72,838
Unrealized Loss, Total	(7,697)	(10,164)
CLOs
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	3,331	6,035
Unrealized Losses, Less than 12 Months	(200)	(466)
Fair Value, Greater than 12 Months	12,186	12,212
Unrealized Losses, Greater than 12 Months	(3,069)	(3,488)
Fair Value, Total	15,517	18,247
Unrealized Loss, Total	(3,269)	(3,954)
Other Securities
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	64,447	90,523
Unrealized Losses, Less than 12 Months	(3,022)	(2,855)
Fair Value, Greater than 12 Months	11,884	726
Unrealized Losses, Greater than 12 Months	(2,126)	(693)
Fair Value, Total	76,331	91,249
Unrealized Loss, Total	$ (5,148)	$ (3,548)