FAIR VALUE MEASUREMENTS - Schedule of Fair Value of Derivative Instruments and Loans Held for Sale (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Derivative notional amount and balance sheet location
Estimated Gain on Sale	$ 43,236	$ 41,684
Total Fair Value Adjustment	43,236	41,684
Derivative assets	25,554	35,536
Derivative Liabilities	(17,726)	(32,697)
Fair Value Adjustment To Loans Held for Sale	35,408	38,845
Loans Held for Sale
Derivative notional amount and balance sheet location
Notional or Principal Amount	1,223,667	1,035,503
Estimated Gain on Sale	26,406	21,399
Interest Rate Movement	9,002	17,446
Total Fair Value Adjustment	35,408	38,845
Fair Value Adjustment To Loans Held for Sale	35,408	38,845
Rate Lock Commitments
Derivative notional amount and balance sheet location
Notional or Principal Amount	662,161	891,514
Estimated Gain on Sale	16,830	20,285
Interest Rate Movement	3,925	10,627
Total Fair Value Adjustment	20,755	30,912
Derivative assets	20,766	30,976
Derivative Liabilities	(11)	(64)
Forward Sale Contracts
Derivative notional amount and balance sheet location
Notional or Principal Amount	1,885,828	1,927,017
Interest Rate Movement	(12,927)	(28,073)
Total Fair Value Adjustment	(12,927)	(28,073)
Derivative assets	4,788	4,560
Derivative Liabilities	$ (17,715)	$ (32,633)