Mortgage-Backed Securities - Maturities of MBS by Estimated Weighted Average Life Classification (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair value
Less than one year, at fair value	$ 24,327	$ 39,516
Greater than one year and less than five years, at fair value	163,242	149,077
Greater than five years and less than ten years, at fair value	557,287	451,758
Greater than ten years, at fair value	1,395,898	505,939
Total maturities, at fair value	2,140,754	1,146,290
Amortized cost
Less than one year, at amortized cost	32,026	43,733
Greater than one year and less than five years, at amortized cost	185,946	161,683
Greater than five years and less than ten years, at amortized cost	516,397	405,359
Greater than ten years, at amortized cost	1,320,325	467,964
Amortized Cost	2,054,694	1,078,739
Non-Agency RMBS - Senior
Fair value
Less than one year, at fair value	17,428	12,086
Greater than one year and less than five years, at fair value	84,870	100,330
Greater than five years and less than ten years, at fair value	248,887	288,283
Greater than ten years, at fair value	293,335	275,429
Total maturities, at fair value	644,520	676,128
Amortized cost
Less than one year, at amortized cost	15,042	4,072
Greater than one year and less than five years, at amortized cost	77,540	95,442
Greater than five years and less than ten years, at amortized cost	186,140	202,295
Greater than ten years, at amortized cost	207,086	203,824
Amortized Cost	485,808	505,633
Non-Agency RMBS - Subordinated
Fair value
Less than one year, at fair value	1,809	3,727
Greater than one year and less than five years, at fair value	28,925	16,221
Greater than five years and less than ten years, at fair value	187,006	100,541
Greater than ten years, at fair value	167,457	156,414
Total maturities, at fair value	385,197	276,903
Amortized cost
Less than one year, at amortized cost	1,894	2,301
Greater than one year and less than five years, at amortized cost	24,915	12,672
Greater than five years and less than ten years, at amortized cost	188,080	104,432
Greater than ten years, at amortized cost	174,545	181,006
Amortized Cost	389,434	300,411
Non-Agency RMBS - Interest-only
Fair value
Less than one year, at fair value	219	269
Greater than one year and less than five years, at fair value	33,562	24,858
Greater than five years and less than ten years, at fair value	55,568	62,934
Greater than ten years, at fair value	2,770	2,714
Total maturities, at fair value	92,119	90,775
Amortized cost
Less than one year, at amortized cost	8,532	9,527
Greater than one year and less than five years, at amortized cost	66,028	46,578
Greater than five years and less than ten years, at amortized cost	76,963	98,632
Greater than ten years, at amortized cost	3,124	3,134
Amortized Cost	154,647	157,871
Agency RMBS - CMO
Fair value
Less than one year, at fair value	0
Greater than one year and less than five years, at fair value	0
Greater than five years and less than ten years, at fair value	63,108
Greater than ten years, at fair value	896,034
Total maturities, at fair value	959,142
Amortized cost
Less than one year, at amortized cost	0
Greater than one year and less than five years, at amortized cost	0
Greater than five years and less than ten years, at amortized cost	63,051
Greater than ten years, at amortized cost	894,060
Amortized Cost	957,111
Agency RMBS - Interest-only
Fair value
Less than one year, at fair value	4,856	15,023
Greater than one year and less than five years, at fair value	9,236	0
Greater than five years and less than ten years, at fair value	2,718	0
Greater than ten years, at fair value	0	0
Total maturities, at fair value	16,810	15,023
Amortized cost
Less than one year, at amortized cost	6,260	19,238
Greater than one year and less than five years, at amortized cost	11,278	0
Greater than five years and less than ten years, at amortized cost	2,164	0
Greater than ten years, at amortized cost	0	0
Amortized Cost	19,702	19,238
Agency CMBS - Project loans
Fair value
Less than one year, at fair value	0	7,797
Greater than one year and less than five years, at fair value	0	0
Greater than five years and less than ten years, at fair value	0	0
Greater than ten years, at fair value	36,302	71,382
Total maturities, at fair value	36,302	79,179
Amortized cost
Less than one year, at amortized cost	0	7,820
Greater than one year and less than five years, at amortized cost	0	0
Greater than five years and less than ten years, at amortized cost	0	0
Greater than ten years, at amortized cost	41,510	80,000
Amortized Cost	41,510	87,820
Agency CMBS - Interest-only
Fair value
Less than one year, at fair value	15	614
Greater than one year and less than five years, at fair value	6,649	7,668
Greater than five years and less than ten years, at fair value	0	0
Greater than ten years, at fair value	0	0
Total maturities, at fair value	6,664	8,282
Amortized cost
Less than one year, at amortized cost	297	775
Greater than one year and less than five years, at amortized cost	6,185	6,991
Greater than five years and less than ten years, at amortized cost	0	0
Greater than ten years, at amortized cost	0	0
Amortized Cost	$ 6,482	$ 7,766