MORTGAGE SERVICING RIGHTS AND MSR FINANCING RECEIVABLES - Schedule of Servicing Fee Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Servicing Asset at Amortized Cost [Line Items]
Change in fair value of derivative instruments	$ 0	$ 8,624	$ 7,189	$ (199)
Gain (loss) on settlement of derivative instruments	232,470	(49,256)	279,945	(76,629)
Servicing revenue, net	806,041	(61,807)	1,837,834	478,751
Change in valuation inputs and assumptions			1,359,992
Excess Spread Financing
Servicing Asset at Amortized Cost [Line Items]
Realization of cash flows		(1,300)		(2,600)
Change in valuation inputs and assumptions		200		1,600
MSRs
Servicing Asset at Amortized Cost [Line Items]
Servicing fee revenue, net and interest income from MSRs and MSR financing receivables	434,789	311,432	856,344	619,264
Ancillary and other fees	34,689	44,744	69,534	85,196
Servicing fee revenue, net and fees	469,478	356,176	925,878	704,460
Realization of cash flows	(180,265)	(297,778)	(380,590)	(637,448)
Change in valuation inputs and assumptions	514,955	(115,986)	1,359,992	425,980
Change in fair value of derivative instruments	0	8,624	7,189	(199)
(Gain) loss realized	1,873	(15,150)	2,179	(16,349)
Gain (loss) on settlement of derivative instruments	0	2,307	(76,814)	2,307
Servicing revenue, net	$ 806,041	$ (61,807)	$ 1,837,834	$ 478,751