GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS - Summary of Allowance for Risk-Sharing Obligations (Detail) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)
Allowance for Risk-Sharing Contracts
Beginning balance	$ 4,622	$ 3,783
Provision (benefit) for risk-sharing obligations	6,398	680	$ 51
Other	451	159
Ending balance	$ 11,471	4,622	$ 3,783	$ 11,471
Number of defaulted loans | loan	2
Amount of specific reserves placed on defaulted at risk loans	$ 6,900			6,900
Number of at risk loans written off				0
Average unpaid principal balance of at risk loans				30,300,000
Fannie Mae DUS program
Allowance for Risk-Sharing Contracts
Maximum quantifiable contingent liability associated with guarantees	$ 7,500,000	$ 6,700,000		$ 7,500,000