GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS - Summary of Allowance for Risk-Sharing Obligations (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($)
Allowance for Risk-Sharing Contracts
Beginning balance	$ 75,313	$ 11,471
Adjustment related to adoption of CECL		31,570
Provision (benefit) for risk-sharing obligations	(12,677)	33,740	$ 6,398
Other		(1,468)
Ending balance	$ 62,636	$ 75,313	11,471
Number of defaulted loans | loan	3	2
Amount of specific reserves placed on defaulted at risk loans	$ 10,300	$ 8,300
Charge off rate for forecasted period	0.03%	0.06%
Reversion period used for determining CECL reserves	1 year
Charge off rate for the remaining period	0.02%
At risk servicing portfolio	$ 115,700,564	$ 107,211,972	$ 93,225,169
Fannie Mae DUS program
Allowance for Risk-Sharing Contracts
Maximum quantifiable contingent liability associated with guarantees	10,100,000	9,000,000
Fannie Mae DUS Program
Allowance for Risk-Sharing Contracts
At risk servicing portfolio	48,000,000
CECL reserve for at risk servicing portfolio	$ 52,300	$ 67,000
Weighted average remaining life of the at risk servicing portfolio	7 years 6 months