EXCESS MORTGAGE SERVICING RIGHTS - Schedule of Activity Related to the Carrying Value of Investments in Excess MSRs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($)
Carrying Value of Investments in Excess MSRs
Beginning balance	$ 6,858,803
Ending balance	7,964,465
Excess MSRs
Carrying Value of Investments in Excess MSRs
Beginning balance	259,198
Interest income	13,016
Other income	2
Proceeds from repayments	(12,191)
Proceeds from sales	(6)
Change in fair value	(2,631)
Ending balance	257,388
Excess MSRs | Mr. Cooper
Carrying Value of Investments in Excess MSRs
Beginning balance	257,573
Interest income	13,007
Other income	2
Proceeds from repayments	(12,113)
Proceeds from sales	(6)
Change in fair value	(2,645)
Ending balance	255,818
Excess MSRs | SLS
Carrying Value of Investments in Excess MSRs
Beginning balance	1,625
Interest income	9
Other income	0
Proceeds from repayments	(78)
Proceeds from sales	0
Change in fair value	14
Ending balance	$ 1,570