FAIR VALUE MEASUREMENTS - Schedule of Fair Value of Derivative Instruments and Loans Held for Sale (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivative notional amount and balance sheet location
Estimated Gain on Sale	$ 30,342	$ 26,904
Total Fair Value Adjustment	30,342	26,904
Derivative assets	20,417	10,357
Derivative Liabilities	(7,455)	(1,850)
Fair Value Adjustment To Loans Held for Sale	17,380	18,397
Loans Held for Sale
Derivative notional amount and balance sheet location
Notional or Principal Amount	770,172	933,432
Estimated Gain on Sale	13,541	19,317
Interest Rate Movement	3,839	(920)
Total Fair Value Adjustment	17,380	18,397
Fair Value Adjustment To Loans Held for Sale	17,380	18,397
Rate Lock Commitments
Derivative notional amount and balance sheet location
Notional or Principal Amount	627,068	241,760
Estimated Gain on Sale	16,801	7,587
Interest Rate Movement	2,778	(678)
Total Fair Value Adjustment	19,579	6,909
Derivative assets	19,638	6,909
Derivative Liabilities	(59)
Forward Sale Contracts
Derivative notional amount and balance sheet location
Notional or Principal Amount	1,397,240	1,175,192
Interest Rate Movement	(6,617)	1,598
Total Fair Value Adjustment	(6,617)	1,598
Derivative assets	779	3,448
Derivative Liabilities	$ (7,396)	$ (1,850)