Financing Agreements - Financing Agreements (Details) $ in Thousands		9 Months Ended	12 Months Ended
	Apr. 04, 2022	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Agreements [Line Items]
Unpaid Principal Balance		$ 7,576,581	$ 6,377,370
Fair Value / Carrying Value		$ 7,289,440	$ 6,378,782
Weighted Average Cost of Funding		3.60%	2.44%
Stock split ratio, common stock	0.25
Convertible Debt | 6.25% Convertible Senior Notes
Financing Agreements [Line Items]
Stock split ratio, common stock	0.25
Agreements with mark-to-market collateral provisions
Financing Agreements [Line Items]
Unpaid Principal Balance		$ 2,124,821	$ 2,562,872
Fair Value / Carrying Value		$ 2,124,791	$ 2,562,299
Weighted Average Cost of Funding		4.22%	1.99%
Agreements with mark-to-market collateral provisions | 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		$ 254,046
Agreements with mark-to-market collateral provisions | 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		731,907
Agreements with mark-to-market collateral provisions | 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		835,077
Fair Value / Carrying Value		273,400
Agreements with mark-to-market collateral provisions | Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		303,791
Fair Value / Carrying Value		254,000
Agreements with mark-to-market collateral provisions | Residential Whole Loans
Financing Agreements [Line Items]
Unpaid Principal Balance		1,981,934	$ 2,403,724
Fair Value / Carrying Value		$ 1,981,904	$ 2,403,151
Weighted Average Cost of Funding		4.23%	2.02%
Weighted Average Term To Maturity (Months)		9 months 21 days	6 months 18 days
Agreements with mark-to-market collateral provisions | Residential Whole Loans | Not Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		$ 932,500
Agreements with mark-to-market collateral provisions | Residential Whole Loans | 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		111,159
Agreements with mark-to-market collateral provisions | Residential Whole Loans | 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		731,907
Agreements with mark-to-market collateral provisions | Residential Whole Loans | 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		835,077
Agreements with mark-to-market collateral provisions | Residential Whole Loans | Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		303,791
Agreements with mark-to-market collateral provisions | Securitized debt
Financing Agreements [Line Items]
Unpaid Principal Balance		142,887	$ 159,148
Fair Value / Carrying Value		$ 142,887	$ 159,148
Weighted Average Cost of Funding		3.94%	1.50%
Weighted Average Term To Maturity (Months)		1 month 15 days	1 month 12 days
Agreements with mark-to-market collateral provisions | Securitized debt | 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		$ 142,887
Agreements with mark-to-market collateral provisions | Securitized debt | 3-6 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		0
Agreements with mark-to-market collateral provisions | Securitized debt | 6-12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		0
Agreements with mark-to-market collateral provisions | Securitized debt | Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		0
Agreements with mark-to-market collateral provisions | Estimated Fair Value
Financing Agreements [Line Items]
Financing agreements, amortized cost		932,500	$ 627,000
Agreements with mark-to-market collateral provisions | Estimated Fair Value | Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value			628,300
Agreements with Non-mark-to-market Collateral Provisions | Residential Whole Loans
Financing Agreements [Line Items]
Unpaid Principal Balance		1,105,441	939,003
Fair Value / Carrying Value		$ 1,104,849	$ 939,540
Weighted Average Cost of Funding		5.46%	3.50%
Weighted Average Term To Maturity (Months)		16 months 15 days	9 months 24 days
Agreements with Non-mark-to-market Collateral Provisions | Residential Whole Loans | Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		$ 604,700
Agreements with Non-mark-to-market Collateral Provisions | Residential Whole Loans | 0-3 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		226,332
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		523,612
Agreements with Non-mark-to-market Collateral Provisions | Residential Whole Loans | Greater than 12 Months
Financing Agreements [Line Items]
Unpaid Principal Balance		355,497
Agreements with Non-mark-to-market Collateral Provisions | Estimated Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value			$ 1,300,000
Financing agreements, amortized cost		604,700	1,300,000
Securitized debt | Residential Whole Loans
Financing Agreements [Line Items]
Unpaid Principal Balance		4,116,330	2,645,495
Fair Value / Carrying Value		$ 3,832,311	$ 2,650,473
Weighted Average Cost of Funding		3.00%	1.96%
Securitized debt | Residential Whole Loans | Held at Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value		$ 2,900,000
Securitized debt | Estimated Fair Value
Financing Agreements [Line Items]
Fair Value / Carrying Value			$ 1,300,000
Financing agreements, amortized cost		3,100,000	1,300,000
Convertible senior notes | Unsecured
Financing Agreements [Line Items]
Unpaid Principal Balance		229,989	230,000
Fair Value / Carrying Value		$ 227,489	$ 226,470
Weighted Average Cost of Funding		6.94%	6.94%