FAIR VALUE MEASUREMENTS - Summary of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Assets
Loans held for sale	$ 1,259,075	$ 1,074,348
Pledged securities	120,302	116,331	$ 109,062	$ 97,859
Derivative assets	25,554	35,536
Liabilities
Derivative liabilities	17,726	32,697
Recurring
Assets
Loans held for sale	1,259,075	1,074,348
Pledged securities	120,302	116,331
Derivative assets	25,554	35,536
Total financial assets	1,404,931	1,226,215
Liabilities
Derivative liabilities	17,726	32,697
Total financial liabilities	17,726	32,697
Level 1 | Recurring
Assets
Pledged securities	5,361	9,469
Total financial assets	5,361	9,469
Level 2 | Recurring
Assets
Loans held for sale	1,259,075	1,074,348
Pledged securities	114,941	106,862
Total financial assets	1,374,016	1,181,210
Level 3 | Recurring
Assets
Derivative assets	25,554	35,536
Total financial assets	25,554	35,536
Liabilities
Derivative liabilities	17,726	32,697
Total financial liabilities	$ 17,726	$ 32,697