FAIR VALUE MEASUREMENTS - Information about Significant Unobservable Inputs Used for Recurring Fair Value Measurements for Level 3 MSRs (Detail) - Fair Value, Measurements, Recurring - Level 3 - Mortgage Servicing Rights - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable input, discount rate	9.00%	9.00%
Unobservable input, prepayment rate	5.30%	4.70%
Unobservable input, delinquency rate	0.00%	0.00%
Unobservable input, cost to service	$ 82	$ 82
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable input, discount rate	12.00%	12.00%
Unobservable input, prepayment rate	23.60%	13.90%
Unobservable input, delinquency rate	5.00%	5.00%
Unobservable input, cost to service	$ 139	$ 138
Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable input, discount rate	9.40%	9.40%
Unobservable input, prepayment rate	11.50%	8.00%
Unobservable input, delinquency rate	2.30%	2.30%
Unobservable input, cost to service	$ 110	$ 110