Mortgage-Backed Securities - Investment Type (Details) - USD ($) $ in Thousands		Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		$ 8,599,616	$ 7,817,400
Amortized Cost		8,671,317	7,912,848
Non-Agency other, Amortized Cost		941,016	1,009,016
Fair Value		8,399,925	7,512,087
Gross Unrealized Gain		3,286	3,283
Gross Unrealized Loss		(156,386)	(175,773)
Fair Value		787,916	836,526
Amortized Cost		7,730,301	6,903,832
Gross Unrealized Gain		41,773	11,081
Gross Unrealized Loss		(160,065)	(239,352)
Fair Value		7,612,009	6,675,561
Residential Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		8,490,912	7,717,764
Amortized Cost		8,452,828	7,695,409
Non-Agency other, Amortized Cost		811,622	827,314
Fair Value		8,185,832	7,302,238
Gross Unrealized Gain		0	0
Gross Unrealized Loss		(150,332)	(167,248)
Fair Value		661,290	660,066
Amortized Cost		7,641,206	6,868,095
Gross Unrealized Gain		41,660	11,081
Gross Unrealized Loss		(158,323)	(237,004)
Fair Value		7,524,543	6,642,172
Commercial Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		108,704	99,636
Amortized Cost		109,578	99,848
Non-Agency other, Amortized Cost		55,000	99,848
Fair Value		106,429	95,463
Gross Unrealized Gain		12	3
Gross Unrealized Loss		(3,271)	(4,388)
Fair Value		51,741	95,463
Amortized Cost		54,578	0
Gross Unrealized Gain		110	0
Gross Unrealized Loss		0	0
Fair Value		54,688	0
Interest-Only-Strip [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Amortized Cost	[1]	108,911	117,591
Non-Agency other, Amortized Cost		74,394	81,854
Fair Value	[1]	107,664	114,386
Gross Unrealized Gain		3,274	3,280
Gross Unrealized Loss		(2,783)	(4,137)
Fair Value		74,885	80,997
Amortized Cost		34,517	35,737
Gross Unrealized Gain		3	0
Gross Unrealized Loss		(1,742)	(2,348)
Fair Value		32,778	33,389
Interest-Only-Strip [Member] | Agency Securities
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		5,779,969	6,196,778
Interest-Only-Strip, Non-Agency CMBS [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		$ 2,050,104	$ 2,450,398

[1] (1) The notional balance for Agency CMBS IO and non-Agency CMBS IO was $5,779,969 and $2,050,104, respectively, as of March 31, 2025, and $6,196,778 and $2,450,398, respectively, as of December 31, 2024.