GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS - Summary of Allowance for Risk-Sharing Obligations (Detail) $ in Thousands	3 Months Ended			6 Months Ended		24 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 USD ($)	Dec. 31, 2013	Jan. 01, 2020 USD ($)
Allowance for Risk-Sharing Contracts
Beginning balance	$ 64,110	$ 11,471	$ 6,682	$ 11,471	$ 4,622
Adjustment related to adoption of ASU 2016-13				31,570
Provision for risk-sharing obligations	5,081		936	27,618	2,988
Other			346	(1,468)	354
Ending balance	69,191	$ 64,110	$ 7,964	$ 69,191	$ 7,964
Number of defaulted loans | loan				2
Amount of specific reserves placed on defaulted at risk loans	$ 6,900			$ 6,900
Number of defaulted at risk loans on which loss sharing settlements were reached | loan				2
Average loss rate for forecasted period				0.01%
Charge off rate in forecasted period		0.07%		0.07%		0.12%
Weighted average charge off rate for the remaining period	0.0176%			0.0176%			0.0176%
Fannie Mae DUS program
Allowance for Risk-Sharing Contracts
Maximum quantifiable contingent liability associated with guarantees	$ 8,300,000			$ 8,300,000
Fannie Mae DUS Program
Allowance for Risk-Sharing Contracts
At risk servicing portfolio	39,900,000			39,900,000
CECL reserve for at risk servicing portfolio	$ 62,300			$ 62,300			$ 34,700
Weighted average remaining life of the at risk servicing portfolio				7 years 8 months 12 days