Short-Term Debt - Assets Sold Under Agreement to Repurchase (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Carrying value:
Unpaid principal balance	$ 6,609,703,000		$ 6,609,703,000
Total loans sold under agreements to repurchase	6,600,997,000		6,600,997,000		$ 3,763,956,000
Loans held for sale	6,565,704,000		6,565,704,000		4,420,691,000
Servicing advances, net	400,764,000		400,764,000		694,038,000
Mortgage servicing rights, at fair value	7,752,292,000		7,752,292,000		7,099,348,000
Other Assets	642,189,000		$ 642,189,000		582,460,000
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]			us-gaap:SecuredOvernightFinancingRateSofrMember
Note Payable
During the period:
Average balance of assets sold under agreements to repurchase	1,730,000,000	$ 2,484,348,000	$ 1,850,621,000	$ 2,353,572,000
Carrying value:
Amortization of debt issuance costs	726,000	689,000	2,200,000	2,400,000
Loan Repo Facility
During the period:
Average balance of assets sold under agreements to repurchase	$ 5,638,124,000	$ 3,208,434,000	$ 4,982,988,000	$ 3,800,502,000
Weighted-average interest rate	6.88%	7.19%	7.04%	7.01%
Total interest expense	$ 102,708,000	$ 62,758,000	$ 279,730,000	$ 209,461,000
Maximum daily amount outstanding	6,608,245,000	4,418,359,000	7,122,796,000	6,358,007,000
Carrying value:
Unpaid principal balance	6,609,703,000		6,609,703,000		3,769,449,000
Unamortized debt issuance costs	(8,706,000)		(8,706,000)		(5,493,000)
Total loans sold under agreements to repurchase	$ 6,600,997,000		$ 6,600,997,000		$ 3,763,956,000
Weighted average interest rate	6.49%		6.49%		7.05%
Available borrowing capacity committed	$ 943,876,000		$ 943,876,000		$ 1,282,040,000
Available borrowing capacity uncommitted	4,803,203,000		4,803,203,000		5,548,511,000
Available borrowing capacity	5,747,079,000		5,747,079,000		6,830,551,000
Amortization of debt issuance costs	5,200,000	$ 4,600,000	17,300,000	$ 10,100,000
Asset Pledged as Collateral without Right
Carrying value:
Loans held for sale	6,503,418,000		6,503,418,000		4,329,501,000
Servicing advances, net	$ 232,766,000		$ 232,766,000		$ 354,831,000
Assets, Pledging Purpose [Extensible Enumeration]	Notes Payable		Notes Payable		Notes Payable
Mortgage servicing rights, at fair value	$ 7,656,519,000		$ 7,656,519,000		$ 7,033,892,000
Other Assets	$ 16,082,000		$ 16,082,000		$ 15,653,000
Asset Pledged as Collateral without Right | Mortgage servicing rights
Carrying value:
Assets, Pledging Purpose [Extensible Enumeration]	Notes Payable		Notes Payable		Notes Payable
Asset Pledged as Collateral without Right | Note Payable | Mortgage servicing rights
Carrying value:
Mortgage servicing rights, at fair value	$ 7,656,519,000		$ 7,656,519,000		$ 7,033,892,000
Asset Pledged as Collateral without Right | Note Payable | Servicing advances
Carrying value:
Servicing advances, net	232,766,000		232,766,000		354,831,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Principal-only stripped MBS
Carrying value:
Principal-only stripped MBS	960,267,000		960,267,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Mortgage servicing rights
Carrying value:
Mortgage servicing rights, at fair value	6,799,741,000		6,799,741,000		6,284,239,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Servicing advances
Carrying value:
Servicing advances, net	232,766,000		232,766,000		354,831,000
Asset Pledged as Collateral without Right | Mortgage loans held for sale | Loan Repo Facility | Loans held for sale
Carrying value:
Loans held for sale	5,954,470,000		5,954,470,000		3,858,977,000
Asset Pledged as Collateral without Right | Deposits.
Carrying value:
Other Assets	16,082,000		16,082,000		15,653,000
Asset Pledged as Collateral without Right | Deposits. | Note Payable | Deposits
Carrying value:
Other Assets	16,082,000		16,082,000		15,653,000
Asset Pledged as Collateral without Right | Deposits. | Loan Repo Facility | Deposits
Carrying value:
Other Assets	$ 16,082,000		$ 16,082,000		$ 15,653,000