GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS - Schedule of Activity Related to Guaranty Obligation (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS
Guaranty obligation, net of accumulated amortization - beginning balance	$ 55,758	$ 49,376	$ 54,695	$ 46,870
Additions, following the sale of loan	1,608	4,731	3,470	9,594
Amortization	(2,494)	(2,347)	(4,761)	(4,696)
Other		(346)	1,468	(354)
Guaranty obligation, net of accumulated amortization - ending balance	$ 54,872	$ 51,414	$ 54,872	$ 51,414