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, 2020	Dec. 31, 2019
Derivative notional amount and balance sheet location
Estimated Gain on Sale	$ 79,763	$ 28,025
Total Fair Value Adjustment	79,763	28,025
Derivative assets	37,290	15,568
Derivative Liabilities	(3,858)	(36)
Fair Value Adjustment to Loans Held for Sale	46,331	12,493
Loans Held for Sale
Derivative notional amount and balance sheet location
Notional or Principal Amount	3,180,956	774,542
Estimated Gain on Sale	53,477	15,826
Interest Rate Movement	(7,146)	(3,333)
Total Fair Value Adjustment	46,331	12,493
Fair Value Adjustment to Loans Held for Sale	46,331	12,493
Rate Lock Commitments
Derivative notional amount and balance sheet location
Notional or Principal Amount	831,286	511,114
Estimated Gain on Sale	26,286	12,199
Interest Rate Movement	(2,928)	(1,975)
Total Fair Value Adjustment	23,358	10,224
Derivative assets	23,358	10,247
Derivative Liabilities		(23)
Forward Sale Contracts
Derivative notional amount and balance sheet location
Notional or Principal Amount	4,012,242	1,285,656
Interest Rate Movement	10,074	5,308
Total Fair Value Adjustment	10,074	5,308
Derivative assets	13,932	5,321
Derivative Liabilities	$ (3,858)	$ (13)