Mortgage-Backed Securities - Investment Type (Details) - USD ($) $ in Thousands		Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		$ 7,817,400	$ 6,143,945
Amortized Cost		7,912,848	6,283,185
Non-Agency other, Amortized Cost		1,009,016	1,131,769
Fair Value		7,512,087	6,038,948
Gross Unrealized Gain		3,283	1,324
Gross Unrealized Loss		(175,773)	(159,826)
Fair Value		836,526	973,267
Amortized Cost		6,903,832	5,151,416
Gross Unrealized Gain		11,081	48,461
Gross Unrealized Loss		(239,352)	(134,196)
Fair Value		6,675,561	5,065,681
Residential Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		7,717,764	6,022,502
Amortized Cost		7,695,409	5,993,922
Non-Agency other, Amortized Cost		827,314	898,420
Fair Value		7,302,238	5,763,532
Gross Unrealized Gain		0	0
Gross Unrealized Loss		(167,248)	(148,606)
Fair Value		660,066	749,814
Amortized Cost		6,868,095	5,095,502
Gross Unrealized Gain		11,081	48,459
Gross Unrealized Loss		(237,004)	(130,243)
Fair Value		6,642,172	5,013,718
Commercial Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		99,636	121,293
Amortized Cost		99,848	121,799
Non-Agency other, Amortized Cost		99,848	106,527
Fair Value		95,463	115,595
Gross Unrealized Gain		3	28
Gross Unrealized Loss		(4,388)	(5,159)
Fair Value		95,463	101,396
Amortized Cost			15,272
Gross Unrealized Gain			0
Gross Unrealized Loss			(1,073)
Fair Value			14,199
Interest-Only-Strip [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Amortized Cost	[1]	117,591	167,314
Non-Agency other, Amortized Cost		81,854	126,672
Fair Value	[1]	114,386	159,718
Gross Unrealized Gain		3,280	1,296
Gross Unrealized Loss		(4,137)	(6,014)
Fair Value		80,997	121,954
Amortized Cost		35,737	40,642
Gross Unrealized Gain		0	2
Gross Unrealized Loss		(2,348)	(2,880)
Fair Value		33,389	37,764
Interest-Only-Strip [Member] | Agency Securities
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		6,196,778	7,723,379
Interest-Only-Strip, Non-Agency CMBS [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		2,450,398	3,860,007
Non-Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		0	150
Non-Agency other, Amortized Cost		0	150
Gross Unrealized Gain			0
Gross Unrealized Loss			(47)
Fair Value		$ 0	$ 103

[1] (1) The notional balance for Agency CMBS IO and non-Agency CMBS IO was $6,196,778 and $2,450,398, respectively, as of December 31, 2024, and $7,723,379 and $3,860,007, respectively, as of December 31, 2023.