Mortgage-Backed Securities - Collateral Characteristics (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 6,231,729	$ 5,488,456
Residential Mortgage-Backed Securities | Non-Agency RMBS - Senior
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 1,023,580	$ 1,073,632
Weighted Average Amortized Cost Basis (in dollars per share)	$ 45.41	$ 45.69
Weighted Average Fair Value (in dollars per share)	$ 62.97	$ 62.98
Weighted Average Coupon	5.70%	5.70%
Weighted Average Yield at Period-End	17.60%	17.30%
Residential Mortgage-Backed Securities | Non-Agency RMBS - Subordinated
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 658,194	$ 583,049
Weighted Average Amortized Cost Basis (in dollars per share)	$ 58.71	$ 50.92
Weighted Average Fair Value (in dollars per share)	$ 58.52	$ 47.49
Weighted Average Coupon	4.50%	3.30%
Weighted Average Yield at Period-End	8.10%	6.70%
Residential Mortgage-Backed Securities | Non-Agency RMBS - Interest-only
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 2,699,126	$ 2,874,680
Weighted Average Amortized Cost Basis (in dollars per share)	$ 5.73	$ 5.49
Weighted Average Fair Value (in dollars per share)	$ 3.41	$ 3.16
Weighted Average Coupon	0.60%	0.50%
Weighted Average Yield at Period-End	4.40%	4.20%
Residential Mortgage-Backed Securities | Agency RMBS - CMO
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 956,977
Weighted Average Amortized Cost Basis (in dollars per share)	$ 100.01
Weighted Average Fair Value (in dollars per share)	$ 100.23
Weighted Average Coupon	6.50%
Weighted Average Yield at Period-End	6.50%
Residential Mortgage-Backed Securities | Agency RMBS - Interest-only
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 384,826	$ 392,284
Weighted Average Amortized Cost Basis (in dollars per share)	$ 5.12	$ 4.90
Weighted Average Fair Value (in dollars per share)	$ 4.37	$ 3.83
Weighted Average Coupon	0.30%	0.10%
Weighted Average Yield at Period-End	5.10%	5.70%
Commercial Mortgage Backed Securities | Agency CMBS - Project loans
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 40,890	$ 86,572
Weighted Average Amortized Cost Basis (in dollars per share)	$ 101.52	$ 101.44
Weighted Average Fair Value (in dollars per share)	$ 88.78	$ 91.46
Weighted Average Coupon	3.50%	4.00%
Weighted Average Yield at Period-End	3.40%	3.80%
Commercial Mortgage Backed Securities | Agency CMBS - Interest-only
Debt Securities, Available-for-sale [Line Items]
Principal or Notional Value	$ 468,136	$ 478,239
Weighted Average Amortized Cost Basis (in dollars per share)	$ 1.38	$ 1.62
Weighted Average Fair Value (in dollars per share)	$ 1.42	$ 1.73
Weighted Average Coupon	0.60%	0.50%
Weighted Average Yield at Period-End	9.20%	8.20%