Financing Agreements - Financing Agreements (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025	Apr. 17, 2024	Jan. 31, 2024
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 11,727,291	$ 10,986,858
Fair Value / Carrying Value	$ 11,520,131	$ 10,940,014
Weighted Average Cost of Funding (as a Percent)	4.38%	4.51%
Secured debt \| Estimated Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		$ 5,800,000
Weighted Average Cost of Funding (as a Percent)	(0.38%)	(0.54%)
Financing agreements, amortized cost	$ 5,700,000	$ 5,900,000
Senior notes \| 8.875% Senior Notes due 2029
Financing Agreements [Line Items]
Stated interest rate (as a percent)	8.875%	8.875%		8.875%
Unpaid Principal Balance	$ 115,000	$ 115,000
Fair Value / Carrying Value	$ 112,671	$ 112,041
Weighted Average Cost of Funding (as a Percent)	9.83%	9.83%
Weighted Average Term to Maturity (Months)	2 years 4 months 17 days	3 years 1 month 13 days
Senior notes \| 9.00% Senior Notes due 2029
Financing Agreements [Line Items]
Stated interest rate (as a percent)	9.00%	9.00%	9.00%
Unpaid Principal Balance	$ 75,000	$ 75,000
Fair Value / Carrying Value	$ 73,240	$ 72,858
Weighted Average Cost of Funding (as a Percent)	9.94%	9.94%
Weighted Average Term to Maturity (Months)	2 years 10 months 13 days	3 years 7 months 13 days
Residential whole loans \| Secured debt
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 6,142,498	$ 6,377,576
Fair Value / Carrying Value	$ 5,939,811	$ 6,336,462
Weighted Average Cost of Funding (as a Percent)	4.99%	5.10%
Residential whole loans \| Secured debt \| Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value	$ 5,500,000
Other \| Other secured financing
Financing Agreements [Line Items]
Unpaid Principal Balance	33,315	$ 23,908
Fair Value / Carrying Value	$ 33,315	$ 23,908
Weighted Average Cost of Funding (as a Percent)	5.94%	6.40%
Weighted Average Term to Maturity (Months)	3 years 9 months 21 days	4 years 6 months 10 days
Unpaid principal balance, with 60-day call provision	$ 30,000
Agreements with mark-to-market collateral provisions
Financing Agreements [Line Items]
Unpaid Principal Balance	5,302,334	$ 4,313,355
Fair Value / Carrying Value	$ 5,301,971	$ 4,312,729
Weighted Average Cost of Funding (as a Percent)	4.30%	4.71%
Agreements with mark-to-market collateral provisions \| 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 4,192,925
Agreements with mark-to-market collateral provisions \| 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	635,512
Agreements with mark-to-market collateral provisions \| 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	54,920
Fair Value / Carrying Value	$ 369,600
Extension period	1 year
Agreements with mark-to-market collateral provisions \| 6-12 Months \| Maximum
Financing Agreements [Line Items]
Extension period	24 months
Agreements with mark-to-market collateral provisions \| Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 418,977
Agreements with mark-to-market collateral provisions \| Estimated Fair Value
Financing Agreements [Line Items]
Financing agreements, amortized cost	8,300	$ 48,200
Agreements with mark-to-market collateral provisions \| Held at Fair Value \| Estimated Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		48,200
Agreements with mark-to-market collateral provisions \| Residential whole loans and REO
Financing Agreements [Line Items]
Unpaid Principal Balance	1,735,361	1,332,593
Fair Value / Carrying Value	$ 1,734,998	$ 1,331,967
Weighted Average Cost of Funding (as a Percent)	5.43%	5.72%
Weighted Average Term to Maturity (Months)	7 months 17 days	11 months 12 days
Agreements with mark-to-market collateral provisions \| Securities
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 3,566,973	$ 2,980,762
Fair Value / Carrying Value	$ 3,566,973	$ 2,980,762
Weighted Average Cost of Funding (as a Percent)	3.81%	4.18%
Weighted Average Term to Maturity (Months)	14 days	10 days
Agreements with mark-to-market collateral provisions \| Securities \| 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 3,566,973
Agreements with mark-to-market collateral provisions \| Securities \| 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	0
Agreements with mark-to-market collateral provisions \| Securities \| 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	0
Agreements with mark-to-market collateral provisions \| Securities \| Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	0
Agreements with mark-to-market collateral provisions \| Residential whole loans
Financing Agreements [Line Items]
Unpaid Principal Balance	1,735,361
Agreements with mark-to-market collateral provisions \| Residential whole loans \| 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	625,952
Agreements with mark-to-market collateral provisions \| Residential whole loans \| 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	635,512
Agreements with mark-to-market collateral provisions \| Residential whole loans \| 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	54,920
Agreements with mark-to-market collateral provisions \| Residential whole loans \| Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	418,977
Agreements with mark-to-market collateral provisions \| Residential whole loans \| Not Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value	8,300
Agreements with non-mark-to-market collateral provisions \| Estimated Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		$ 61,100
Financing agreements, amortized cost	18,700	61,100
Agreements with non-mark-to-market collateral provisions \| Residential whole loans and REO
Financing Agreements [Line Items]
Unpaid Principal Balance	59,144	82,019
Fair Value / Carrying Value	$ 59,123	$ 82,016
Weighted Average Cost of Funding (as a Percent)	5.93%	6.44%
Weighted Average Term to Maturity (Months)	4 months 28 days	1 year 2 months 15 days
Agreements with non-mark-to-market collateral provisions \| Residential whole loans
Financing Agreements [Line Items]
Unpaid Principal Balance	$ 59,144
Agreements with non-mark-to-market collateral provisions \| Residential whole loans \| 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	40,449
Agreements with non-mark-to-market collateral provisions \| Residential whole loans \| 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	0
Agreements with non-mark-to-market collateral provisions \| Residential whole loans \| 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	0
Agreements with non-mark-to-market collateral provisions \| Residential whole loans \| Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance	18,695
Agreements with non-mark-to-market collateral provisions \| Residential whole loans \| Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value	$ 18,700
Impact of net Swap carry
Financing Agreements [Line Items]
Weighted Average Cost of Funding (as a Percent)	(0.38%)	(0.54%)