FAIR VALUE MEASUREMENTS - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Loans
Mortgage servicing rights	$ 2,909,134	$ 2,122,196	$ 1,748,209
Liabilities
Participations issued	1,154,816	1,103,835
U.S. Treasury securities sold, not yet purchased	2,470,629	2,132,751
Residential mortgage loans
Loans
Residential mortgage loans	25,520,090	15,660,706
Fair Value, Measurements, Recurring
Assets
Agency mortgage-backed securities	67,434,068	66,308,788
Credit risk transfer securities	754,915	974,059
Loans
Mortgage servicing rights	2,909,134	2,122,196
Derivative assets
Interest rate swaps	21,226	26,344
Other derivatives	204,125	136,213
Total assets	98,411,022	87,559,024
Liabilities
Debt issued by securitization vehicles	19,540,678	11,600,338
Participations issued	1,154,816	1,103,835
U.S. Treasury securities sold, not yet purchased	2,470,629	2,132,751
Derivative liabilities
Interest rate swaps	7,212	83,051
Other derivatives	52,374	219,244
Total liabilities	23,225,709	15,139,219
Fair Value, Measurements, Recurring \| Asset Transferred or Pledged
Loans
Assets transferred or pledged to securitization vehicles	21,973,188	13,307,622
Fair Value, Measurements, Recurring \| Non-Agency mortgage-backed securities
Assets
Mortgage-backed securities	1,493,186	2,108,274
Fair Value, Measurements, Recurring \| Commercial mortgage-backed securities
Assets
Mortgage-backed securities	74,278	222,444
Fair Value, Measurements, Recurring \| Residential mortgage loans
Loans
Residential mortgage loans	3,546,902	2,353,084
Fair Value, Measurements, Recurring \| Level 1
Assets
Agency mortgage-backed securities	0	0
Credit risk transfer securities	0	0
Loans
Mortgage servicing rights	0	0
Derivative assets
Interest rate swaps	0	0
Other derivatives	190,980	0
Total assets	190,980	0
Liabilities
Debt issued by securitization vehicles	0	0
Participations issued	0	0
U.S. Treasury securities sold, not yet purchased	2,470,629	2,132,751
Derivative liabilities
Interest rate swaps	0	0
Other derivatives	16,650	179,835
Total liabilities	2,487,279	2,312,586
Fair Value, Measurements, Recurring \| Level 1 \| Asset Transferred or Pledged
Loans
Assets transferred or pledged to securitization vehicles	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Non-Agency mortgage-backed securities
Assets
Mortgage-backed securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Commercial mortgage-backed securities
Assets
Mortgage-backed securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Residential mortgage loans
Loans
Residential mortgage loans	0	0
Fair Value, Measurements, Recurring \| Level 2
Assets
Agency mortgage-backed securities	67,434,068	66,308,788
Credit risk transfer securities	754,915	974,059
Loans
Mortgage servicing rights	0	0
Derivative assets
Interest rate swaps	21,226	26,344
Other derivatives	13,145	136,213
Total assets	95,310,908	85,436,828
Liabilities
Debt issued by securitization vehicles	19,540,678	11,600,338
Participations issued	1,154,816	1,103,835
U.S. Treasury securities sold, not yet purchased	0	0
Derivative liabilities
Interest rate swaps	7,212	83,051
Other derivatives	35,724	39,409
Total liabilities	20,738,430	12,826,633
Fair Value, Measurements, Recurring \| Level 2 \| Asset Transferred or Pledged
Loans
Assets transferred or pledged to securitization vehicles	21,973,188	13,307,622
Fair Value, Measurements, Recurring \| Level 2 \| Non-Agency mortgage-backed securities
Assets
Mortgage-backed securities	1,493,186	2,108,274
Fair Value, Measurements, Recurring \| Level 2 \| Commercial mortgage-backed securities
Assets
Mortgage-backed securities	74,278	222,444
Fair Value, Measurements, Recurring \| Level 2 \| Residential mortgage loans
Loans
Residential mortgage loans	3,546,902	2,353,084
Fair Value, Measurements, Recurring \| Level 3
Assets
Agency mortgage-backed securities	0	0
Credit risk transfer securities	0	0
Loans
Mortgage servicing rights	2,909,134	2,122,196
Derivative assets
Interest rate swaps	0	0
Other derivatives	0	0
Total assets	2,909,134	2,122,196
Liabilities
Debt issued by securitization vehicles	0	0
Participations issued	0	0
U.S. Treasury securities sold, not yet purchased	0	0
Derivative liabilities
Interest rate swaps	0	0
Other derivatives	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Asset Transferred or Pledged
Loans
Assets transferred or pledged to securitization vehicles	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Non-Agency mortgage-backed securities
Assets
Mortgage-backed securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Commercial mortgage-backed securities
Assets
Mortgage-backed securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Residential mortgage loans
Loans
Residential mortgage loans	$ 0	$ 0

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Fair value of obligations incurred from short sales.

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