SECURED FINANCING - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Repurchase Agreements:
Netted amounts	$ 75,118,963	$ 65,688,923	[1]
Repurchase agreements, weighted average remaining maturities	49 days	32 days
Repurchase agreements weighted average rate	4.36%	4.76%
Repurchase agreement amount	$ 4,300,000
Remaining capacity of repurchase agreement	2,500,000
Fair value of collateral received for reverse repurchase agreements	4,500,000	$ 2,600,000
Fair value of securities sold	2,400,000	2,500,000
Other secured financing	$ 1,025,000	$ 750,000	[1]
Debt weighted average interest rate	6.94%	7.21%
Secured financings and interest rate swaps - collateral held, estimated fair value	$ 81,700,000	$ 71,800,000
Secured financings and interest rate swaps - collateral held, accrued interest	374,600	332,700
Line of Credit | Mortgage Servicing Rights Committed Credit Facility
Repurchase Agreements:
Credit facility, maximum borrowing capacity	$ 2,100,000	$ 1,600,000
Minimum
Repurchase Agreements:
Debt instrument, maturity	2 months	1 month
Maximum
Repurchase Agreements:
Debt instrument, maturity	2 years	2 years

[1] (1)Derived from the audited consolidated financial statements at December 31, 2024.