Investment in Securities (Unrealized Loss Positions Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 1,298,528	$ 1,094,937
Unrealized Losses, Less than 12 Months	(70,656)	(16,006)
Fair Value, Greater than 12 Months	205,915	44,888
Unrealized Losses, Greater than 12 Months	(18,967)	(6,414)
Fair Value, Total	1,504,443	1,139,825
Unrealized Loss, Total	(89,623)	(22,420)
Agency RMBS
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	1,226,857	1,083,017
Unrealized Losses, Less than 12 Months	(65,638)	(15,190)
Fair Value, Greater than 12 Months	185,703	39,124
Unrealized Losses, Greater than 12 Months	(16,704)	(1,815)
Fair Value, Total	1,412,560	1,122,141
Unrealized Loss, Total	(82,342)	(17,005)
Non-Agency RMBS
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	67,428	11,296
Unrealized Losses, Less than 12 Months	(3,617)	(802)
Fair Value, Greater than 12 Months	3,751	4,462
Unrealized Losses, Greater than 12 Months	(365)	(1,850)
Fair Value, Total	71,179	15,758
Unrealized Loss, Total	(3,982)	(2,652)
CLOs
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	2,923	624
Unrealized Losses, Less than 12 Months	(20)	(14)
Fair Value, Greater than 12 Months	16,461	1,302
Unrealized Losses, Greater than 12 Months	(1,893)	(2,749)
Fair Value, Total	19,384	1,926
Unrealized Loss, Total	(1,913)	$ (2,763)
Other Securities
Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	1,320
Unrealized Losses, Less than 12 Months	(1,381)
Fair Value, Greater than 12 Months	0
Unrealized Losses, Greater than 12 Months	(5)
Fair Value, Total	1,320
Unrealized Loss, Total	$ (1,386)