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	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 83	$ 81
Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	223	135
Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 128	$ 107
Discount Rate | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.090	0.090
Discount Rate | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.120	0.120
Discount Rate | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.094	0.093
Prepayment Rate | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.146	0.063
Prepayment Rate | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.480	0.266
Prepayment Rate | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.340	0.137
Delinquency Rate | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.000	0.000
Delinquency Rate | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.170	0.040
Delinquency Rate | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.049	0.022