Mortgage-Backed Securities - Investment Type (Details) - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		$ 6,143,945	$ 3,236,285
Amortized Cost		6,283,185	3,522,256
Fair Value		6,038,948	3,112,705
Amortized cost		1,131,769	1,288,269
Gross Unrealized Gain		1,324	507
Gross Unrealized Loss		(159,826)	(181,853)
Fair Value		973,267	1,106,923
Amortized Cost		5,151,416	2,233,987
Gross Unrealized Gain		48,461	0
Gross Unrealized Loss		(134,196)	(228,205)
Fair Value		5,065,681	2,005,782
Residential Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		6,022,502	3,104,498
Amortized Cost		5,993,922	3,150,873
Fair Value		5,763,532	2,762,878
Amortized cost		898,420	977,624
Gross Unrealized Gain		0	0
Gross Unrealized Loss		(148,606)	(164,949)
Fair Value		749,814	812,675
Amortized Cost		5,095,502	2,173,249
Gross Unrealized Gain		48,459	0
Gross Unrealized Loss		(130,243)	(223,046)
Fair Value		5,013,718	1,950,203
Commercial Mortgage Backed Securities [Member] | Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		121,293	131,578
Amortized Cost		121,799	132,333
Fair Value		115,595	124,690
Amortized cost		106,527	117,031
Gross Unrealized Gain		28	0
Gross Unrealized Loss		(5,159)	(6,474)
Fair Value		101,396	110,557
Amortized Cost		15,272	15,302
Gross Unrealized Gain		0	0
Gross Unrealized Loss		(1,073)	(1,169)
Fair Value		14,199	14,133
Interest-Only-Strip [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Amortized Cost	[1]	167,314	238,841
Fair Value	[1]	159,718	224,985
Amortized cost		126,672	193,405
Gross Unrealized Gain		1,296	507
Gross Unrealized Loss		(6,014)	(10,373)
Fair Value		121,954	183,539
Amortized Cost		40,642	45,436
Gross Unrealized Gain		2	0
Gross Unrealized Loss		(2,880)	(3,990)
Fair Value		37,764	41,446
Interest-Only-Strip, Agency CMBS [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Notional balance		7,723,379	9,711,981
Interest-Only-Strip, Non-Agency CMBS [Member]
Debt Securities, Trading and Available-for-sale [Abstract]
Notional balance		3,860,007	6,280,761
Non-Agency MBS
Debt Securities, Trading and Available-for-sale [Abstract]
Par Value		150	209
Fair Value		103	152
Amortized cost		150	209
Gross Unrealized Gain		0	0
Gross Unrealized Loss		(47)	(57)
Fair Value		$ 103	$ 152

[1] (1) The notional balance for Agency CMBS IO and non-Agency CMBS IO was $7,723,379 and $3,860,007, respectively, as of December 31, 2023, and $9,711,981 and $6,280,761, respectively, as of December 31, 2022.