GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS - Schedule of Activity Related to Guaranty Obligation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS
Guaranty obligation, net of accumulated amortization - beginning balance	$ 54,872	$ 51,414	$ 54,695	$ 46,870
Additions, following the sale of loan	876	3,729	4,346	13,323
Amortization	(2,274)	(2,365)	(7,035)	(7,061)
Other		(122)	1,468	(476)
Guaranty obligation, net of accumulated amortization - ending balance	$ 53,474	$ 52,656	$ 53,474	$ 52,656