Use of Special Purpose Entities and Variable Interest Entities - Loan Securitization Transaction (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Weighted Average Cost of Funding	3.95%	3.70%
Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Aggregate unpaid principal balance of residential whole loans sold	$ 6,747,911	$ 6,079,749
Outstanding amount of Senior Bonds, at carrying value	889,928	922,220
Outstanding amount of Senior Bonds, at fair value	2,940,381	2,435,370
Outstanding amount of Senior Bonds, total	$ 3,830,309	$ 3,357,590
Weighted Average Cost of Funding	2.96%	3.38%
Weighted average contractual maturity of Senior Bonds	37 years	38 years
Cash received	$ 5,807,409	$ 5,286,305
Debt issuance cost	2,300	2,900
Senior Notes
Variable Interest Entity [Line Items]
Cash received	523,200
Senior Notes \| Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Debt instrument, face amount	5,856,311	5,333,090
Proceeds from Senior bond sold with Step up feature	$ 2,400,000	1,900
Senior Notes \| Asset-backed Securities, Securitized Loans and Receivables \| Minimum
Variable Interest Entity [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Debt instrument, coupon step-up period	24 months
Senior Notes \| Asset-backed Securities, Securitized Loans and Receivables \| Maximum
Variable Interest Entity [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Debt instrument, coupon step-up period	48 months
Senior Notes \| Asset-backed Securities, Securitized Loans and Receivables \| Median
Variable Interest Entity [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Senior Support Certificates \| Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Debt instrument, face amount	$ 857,176	$ 715,640

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