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	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 81	$ 83
Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	107	108
Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 97	$ 98
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	0.090	0.094
Prepayment rate  | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.110	0.193
Prepayment rate  | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.392	0.555
Prepayment rate  | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.269	0.420
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	0.060	0.060
Delinquency rate | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.025	0.025