Use of Special Purpose Entities and Variable Interest Entities - Loan Securitization Transaction (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Weighted average fixed rate for Senior Bonds issued	3.96%	3.96%	3.70%
Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Aggregate unpaid principal balance of residential whole loans sold	$ 7,119,527	$ 7,119,527	$ 6,079,749
Outstanding amount of Senior Bonds, at carrying value	845,796	845,796	922,220
Outstanding amount of Senior Bonds, at fair value	3,123,478	3,123,478	2,435,370
Outstanding amount of Senior Bonds, total	$ 3,969,274	$ 3,969,274	$ 3,357,590
Weighted average fixed rate for Senior Bonds issued	3.85%	3.85%	3.38%
Weighted average contractual maturity of Senior Bonds		37 years	38 years
Cash received		$ 6,103,771	$ 5,286,305
Debt issuance cost	$ 2,000	2,000	2,900
Senior Notes
Variable Interest Entity [Line Items]
Cash received	308,800	832,000
Senior Notes | Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Debt instrument, face amount	6,165,095	6,165,095	5,333,090
Proceeds from Senior bond sold with Step up feature		$ 2,600,000	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 | Median
Variable Interest Entity [Line Items]
Debt instrument, basis spread on variable rate		2.00%
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 Support Certificates | Asset-backed Securities, Securitized Loans and Receivables
Variable Interest Entity [Line Items]
Debt instrument, face amount	$ 919,974	$ 919,974	$ 715,640