Short-Term Debt - Assets Sold Under Agreement to Repurchase (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Carrying value:
Unpaid principal balance	$ 7,138,415,000		$ 7,138,415,000
Total loans sold under agreements to repurchase	7,130,423,000		7,130,423,000		$ 8,685,207,000
Loans held for sale	7,490,473,000		7,490,473,000		8,217,468,000
Servicing advances, net	396,006,000		396,006,000		568,512,000
Mortgage servicing rights, at fair value	9,653,942,000		9,653,942,000		8,744,528,000
Other Assets	742,395,000		$ 742,395,000		770,081,000
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	1,393,315,000	$ 1,730,000,000	$ 1,649,964,000	$ 1,850,621,000
Carrying value:
Amortization of debt issuance costs	249,000	726,000	3,400,000	2,200,000
Loan Repo Facility
During the period:
Average balance of assets sold under agreements to repurchase	$ 7,719,152,000	$ 5,638,124,000	$ 7,010,169,000	$ 4,982,988,000
Weighted-average interest rate	5.95%	6.88%	5.97%	7.04%
Total interest expense	$ 121,170,000	$ 102,708,000	$ 328,084,000	$ 279,730,000
Maximum daily amount outstanding	8,926,829,000	6,608,245,000	8,926,829,000	7,122,796,000
Carrying value:
Unpaid principal balance	7,138,415,000		7,138,415,000		8,692,756,000
Unamortized debt issuance costs	(7,992,000)		(7,992,000)		(7,549,000)
Total loans sold under agreements to repurchase	$ 7,130,423,000		$ 7,130,423,000		$ 8,685,207,000
Weighted average interest rate	5.55%		5.55%		5.89%
Available borrowing capacity committed	$ 1,595,464,000		$ 1,595,464,000		$ 460,000,000
Available borrowing capacity uncommitted	3,762,269,000		3,762,269,000		3,104,026,000
Available borrowing capacity	5,357,733,000		5,357,733,000		3,564,026,000
Amortization of debt issuance costs	5,300,000	$ 5,200,000	15,300,000	$ 17,300,000
Asset Pledged as Collateral without Right
Carrying value:
Loans held for sale	7,433,850,000		7,433,850,000		8,140,834,000
Servicing advances, net	$ 261,752,000		$ 261,752,000		$ 357,939,000
Assets, Pledging Purpose [Extensible Enumeration]	Notes Payable		Notes Payable		Notes Payable
Mortgage servicing rights, at fair value	$ 9,440,264,000		$ 9,440,264,000		$ 8,609,388,000
Other Assets	$ 11,848,000		$ 11,848,000		$ 16,697,000
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:
Assets, Pledging Purpose [Extensible Enumeration]	Notes Payable		Notes Payable		Notes Payable
Mortgage servicing rights, at fair value	$ 9,440,264,000		$ 9,440,264,000		$ 8,609,388,000
Asset Pledged as Collateral without Right | Note Payable | Servicing advances
Carrying value:
Servicing advances, net	261,752,000		261,752,000		357,939,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Principal-only stripped MBS
Carrying value:
Principal-only stripped MBS	774,021,000		774,021,000		825,865,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Mortgage servicing rights
Carrying value:
Mortgage servicing rights, at fair value	8,197,102,000		8,197,102,000		7,488,539,000
Asset Pledged as Collateral without Right | Loan Repo Facility | Servicing advances
Carrying value:
Servicing advances, net	261,752,000		261,752,000		357,939,000
Asset Pledged as Collateral without Right | Mortgage loans held for sale | Loan Repo Facility | Loans held for sale
Carrying value:
Loans held for sale	6,693,386,000		6,693,386,000		7,612,832,000
Asset Pledged as Collateral without Right | Deposits.
Carrying value:
Other Assets	11,848,000		11,848,000		16,697,000
Asset Pledged as Collateral without Right | Deposits. | Deposits
Carrying value:
Other Assets	11,848,000		11,848,000		16,697,000
Asset Pledged as Collateral without Right | Deposits. | Loan Repo Facility | Deposits
Carrying value:
Other Assets	$ 11,848,000		$ 11,848,000		$ 16,697,000