Net Interest Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Interest income:
Interest income	$ 225,470,000	$ 166,552,000	$ 582,707,000	$ 467,982,000
Interest expense:
Interest expense	217,597,000	156,863,000	591,237,000	467,276,000
Net interest income (expense)	7,873,000	9,689,000	(8,530,000)	706,000
Nonrelated Party
Interest income:
Cash and short-term investments	15,641,000	15,814,000	43,395,000	53,186,000
Principal-only stripped mortgage-backed securities	20,412,000		29,756,000
Loans held for sale	80,103,000	65,641,000	231,807,000	205,414,000
Placement fees relating to custodial funds	109,201,000	85,076,000	277,564,000	209,319,000
Other	113,000		165,000
Interest expense:
Assets sold under agreements to repurchase	102,708,000	62,758,000	279,730,000	209,461,000
Mortgage loan participation purchase and sale agreements	4,411,000	4,383,000	12,597,000	11,768,000
Notes payable secured by mortgage servicing assets	39,265,000	55,676,000	125,203,000	150,271,000
Unsecured senior notes	51,147,000	23,949,000	133,947,000	71,065,000
Interest shortfall on repayments of mortgage loans serviced for Agency securitizations	15,711,000	6,857,000	29,734,000	16,781,000
Interest on mortgage loan impound deposits	3,450,000	2,888,000	8,399,000	7,080,000
Other	905,000	352,000	1,627,000	850,000
Interest expense	217,597,000	156,863,000	591,237,000	467,276,000
Related Party | Townsgate Closing Services, LLC
Interest income:
Interest income	0	21,000	20,000	63,000
Loan Repo Facility
Interest expense:
Assets sold under agreements to repurchase	$ 102,708,000	$ 62,758,000	$ 279,730,000	$ 209,461,000