FAIR VALUE MEASUREMENTS - Financial Assets Measured at Fair Value on a Recurring Basis using Level 3 Inputs (Details) - Recurring Basis - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	$ 16,966,963	$ 15,619,730	$ 17,356,207	$ 14,427,743
Transfers:
Transfers out of Level 3	(59,136)	(227,216)	(845,247)	(264,142)
Transfers to Level 3	83	193,997	41,832	82,325
Computershare Acquisition (Note 3)				696,462
Gain (Loss) Included in Net Income:
Credit losses on securities	707	(273)	104	(1,187)
Included in servicing revenue	(401,342)	(755,953)	(1,134,443)	(748,702)
Other factors	6,864	(8,284)	61,027	23,072
Instrument-specific credit risk	(17,373)	30,568	(46,029)	25,384
Gain (loss) on settlement of investments, net		(137)		(757)
Other income (loss), net	9,636	25,757	29,665	21,367
Gains (losses) included in OCI	5,716	10,761	13,667	7,287
Interest income (expense)	19,213	26,255	66,503	80,815
Purchases, Sales and Repayments:
Purchases, net	409,903	463,717	1,073,686	1,319,150
Sales and settlement fundings	(24,152)	(105,476)	(52,968)	(154,506)
Proceeds from repayments	(1,288,680)	(848,529)	(3,412,411)	(2,817,554)
Originations and other	1,709,985	1,026,369	4,186,794	2,754,529
Balance, ending	17,338,387	15,451,286	17,338,387	15,451,286
Excess MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	345,677	395,606	369,162	271,150
Transfers:
Transfers out of Level 3	0	0	0	0
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				(1,032)
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	(1,637)	(9,448)	(3,242)	11,599
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		0		(656)
Other income (loss), net	598	0	598	0
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	7,851	8,371	21,150	18,893
Purchases, Sales and Repayments:
Purchases, net	0	0	0	122,887
Sales and settlement fundings	(1,060)	0	(1,105)	0
Proceeds from repayments	(16,761)	(18,606)	(51,895)	(46,918)
Originations and other	0	0	0	0
Balance, ending	334,668	375,923	334,668	375,923
MSRs And MSR Financing Receivables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	10,360,063	9,693,331	10,321,671	8,405,938
Transfers:
Transfers out of Level 3	0	0	0	0
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				697,494
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	(401,342)	(755,953)	(1,134,443)	(748,702)
Other factors	0	0	0	0
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	0	0	0	0
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	0	0	0	0
Purchases, Sales and Repayments:
Purchases, net	0	0	0	0
Sales and settlement fundings	81	344	2,605	2,748
Proceeds from repayments	0	0	0	0
Originations and other	430,964	363,267	1,199,933	943,511
Balance, ending	10,389,766	9,300,989	10,389,766	9,300,989
Servicer Advances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	312,986	357,220	339,646	376,881
Transfers:
Transfers out of Level 3	0	0	0	(7,873)
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	873	(9,923)	(654)	(3,535)
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	0	0	0	0
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	5,001	5,395	15,601	18,649
Purchases, Sales and Repayments:
Purchases, net	169,957	189,609	520,334	590,261
Sales and settlement fundings	0	0	0	0
Proceeds from repayments	(186,539)	(200,998)	(572,649)	(633,080)
Originations and other	0	0	0	0
Balance, ending	302,278	341,303	302,278	341,303
Non-Agency
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	739,143	548,046	552,797	577,543
Transfers:
Transfers out of Level 3	0	(7,384)	0	(7,384)
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	707	(273)	104	(1,187)
Included in servicing revenue	0	0	0	0
Other factors	(2,852)	7,631	1,124	7,631
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		(137)		(137)
Other income (loss), net	0	(939)	0	0
Gains (losses) included in OCI	5,716	10,761	13,667	12,641
Interest income (expense)	9,855	6,960	26,427	21,828
Purchases, Sales and Repayments:
Purchases, net	0	37,430	210,826	51,330
Sales and settlement fundings	0	0	0	0
Proceeds from repayments	(31,124)	(22,378)	(83,500)	(82,548)
Originations and other	0	0	0	0
Balance, ending	721,445	579,717	721,445	579,717
CLOs And Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	87,853	261,492	810,431	226,486
Transfers:
Transfers out of Level 3	(59,136)	(219,832)	(844,389)	(219,832)
Transfers to Level 3	83	0	39,751	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	0	3,342	0	3,342
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		0		36
Other income (loss), net	152	(4,646)	605	0
Gains (losses) included in OCI	0	0	0	(5,354)
Interest income (expense)	0	0	0	0
Purchases, Sales and Repayments:
Purchases, net	10,897	25,032	69,199	91,649
Sales and settlement fundings	(28,324)	0	(64,072)	0
Proceeds from repayments	0	0	0	(30,939)
Originations and other	0	0	0	0
Balance, ending	11,525	65,388	11,525	65,388
Residential Mortgage Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	430,194	384,587	455,726	513,381
Transfers:
Transfers out of Level 3	0	0	(858)	(28,985)
Transfers to Level 3	0	193,997	2,081	82,325
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	1,642	7,788	14,482	16,536
Instrument-specific credit risk	222	12,234	(6,228)	28,127
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	274	6,285	2,034	10,633
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	0	0	0	0
Purchases, Sales and Repayments:
Purchases, net	292	1,714	830	248,606
Sales and settlement fundings	0	(111,718)	(7,216)	(173,250)
Proceeds from repayments	(12,555)	(21,687)	(45,028)	(53,773)
Originations and other	(1,152)	3,102	3,094	(167,298)
Balance, ending	418,917	476,302	418,917	476,302
Consumer Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	465,231	946,367	665,565	1,274,005
Transfers:
Transfers out of Level 3	0	0	0	0
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	32,479	(29,248)	19,156	(49,003)
Instrument-specific credit risk	(5,875)	10,896	(12,263)	(20,738)
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	0	0	0	0
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	(3,543)	5,353	3,157	21,331
Purchases, Sales and Repayments:
Purchases, net	220,962	0	220,962	0
Sales and settlement fundings	5,151	5,898	16,820	15,996
Proceeds from repayments	(116,258)	(133,689)	(315,250)	(436,014)
Originations and other	0	0	0	0
Balance, ending	598,147	805,577	598,147	805,577
Other Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	760,591	491,712	700,942	549,446
Transfers:
Transfers out of Level 3	0	0	0	(68)
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	(33,152)	(351)	9,584	(418)
Instrument-specific credit risk	0	0	0	0
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	8,612	25,057	26,428	10,734
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	49	176	168	114
Purchases, Sales and Repayments:
Purchases, net	4,361	209,932	48,101	214,417
Sales and settlement fundings	0	0	0	0
Proceeds from repayments	(10,037)	(7,197)	(54,799)	(54,835)
Originations and other	0	0	0	(61)
Balance, ending	730,424	719,329	730,424	719,329
RTLs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	3,465,225	2,541,369	3,140,267	2,232,913
Transfers:
Transfers out of Level 3	0	0	0	0
Transfers to Level 3	0	0	0	0
Computershare Acquisition (Note 3)				0
Gain (Loss) Included in Net Income:
Credit losses on securities	0	0	0	0
Included in servicing revenue	0	0	0	0
Other factors	9,511	21,925	20,577	36,920
Instrument-specific credit risk	(11,720)	7,438	(27,538)	17,995
Gain (loss) on settlement of investments, net		0		0
Other income (loss), net	0	0	0	0
Gains (losses) included in OCI	0	0	0	0
Interest income (expense)	0	0	0	0
Purchases, Sales and Repayments:
Purchases, net	3,434	0	3,434	0
Sales and settlement fundings	0	0	0	0
Proceeds from repayments	(915,406)	(443,974)	(2,289,290)	(1,479,447)
Originations and other	1,280,173	660,000	2,983,767	1,978,377
Balance, ending	$ 3,831,217	$ 2,786,758	$ 3,831,217	$ 2,786,758