BUSINESS ACQUISITIONS - Schedule of Measurement Period Adjustments (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 23, 2021	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Total Consideration						$ 1,239,700
Assets
Mortgage servicing rights, at fair value						387,200
Residential mortgage loans, held-for-sale, at fair value						627,400
Residential mortgage loans subject to repurchase						0
Cash and cash equivalents						1,800
Restricted cash						0
Servicer advance receivable						238,000
Intangible assets						22,200
Other assets						71,400
Total Assets Acquired						1,348,000
Liabilities
Secured financing agreements						0
Secured notes and bonds payable						0
Residential mortgage loans repurchase liability						0
Accrued expenses and other liabilities						63,900
Total Liabilities Assumed						63,900
Net Assets						1,284,100
Bargain purchase gain				$ (6,024)	$ 0	$ (49,539)
Caliber Home Loans Inc
Business Acquisition [Line Items]
Total Consideration			$ 1,318,500	1,318,500
Assets
Mortgage servicing rights, at fair value		$ 1,507,500	1,507,500	1,507,500
Residential mortgage loans, held-for-sale, at fair value		7,685,700	7,685,700	7,685,700
Residential mortgage loans subject to repurchase		666,800	666,800	666,800
Cash and cash equivalents		472,700	472,700	472,700
Restricted cash		30,600	30,600	30,600
Servicer advance receivable		108,300	108,300	108,300
Intangible assets		41,000	41,000	41,000
Increase to other assets		4,300
Other assets		609,700	605,400	609,700
Total Assets Acquired		11,122,300	11,118,000	11,122,300
Total Assets Acquired		4,300
Liabilities
Secured financing agreements		7,090,600	7,090,600	7,090,600
Secured notes and bonds payable		1,121,800	1,121,800	1,121,800
Residential mortgage loans repurchase liability		666,800	666,800	666,800
Accrued expenses and other liabilities		918,600	917,000	918,600
Accrued expenses and other liabilities		1,600
Total Liabilities Assumed		9,797,800	9,796,200	9,797,800
Total Liabilities Assumed		1,600
Net Assets		1,324,500	1,321,800	1,324,500
Net Assets		2,700
Bargain purchase gain	$ (3,300)		$ (3,300)	$ (6,000)
Goodwill (bargain purchase gain)		$ (2,700)