EXCESS MORTGAGE SERVICING RIGHTS - Schedule of Activity Related to the Carrying Value of Investments in Excess MSRs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Carrying Value of Investments in Excess MSRs
Beginning balance	$ 4,585,841	$ 5,686,233
Ending balance	6,858,803	4,585,841
Excess MSRs
Carrying Value of Investments in Excess MSRs
Beginning balance		379,747
Interest income	20,296	28,352
Other income	78	(12,123)
Proceeds from repayments	(56,052)	(67,745)
Proceeds from sales	(984)	(1,061)
Change in fair value	(15,078)	(16,232)
Excess MSRs | Mr. Cooper
Carrying Value of Investments in Excess MSRs
Beginning balance	309,009	377,692
Interest income	20,355	28,217
Other income	403	(12,123)
Proceeds from repayments	(55,702)	(67,340)
Proceeds from sales	(984)	(1,061)
Change in fair value	(15,508)	(16,376)
Ending balance	257,573	309,009
Excess MSRs | SLS
Carrying Value of Investments in Excess MSRs
Beginning balance	1,929	2,055
Interest income	(59)	135
Other income	(325)	0
Proceeds from repayments	(350)	(405)
Proceeds from sales	0	0
Change in fair value	430	144
Ending balance	$ 1,625	$ 1,929