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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	6 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 99
Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	106
Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	101
Interest in MSRs | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	78
Interest in MSRs | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	86
Interest in MSRs | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	85
Consolidated VIEs | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	84	$ 83
Consolidated VIEs | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	114	108
Consolidated VIEs | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Unobservable input, cost to service	$ 99	$ 98
Discount rate | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.018
Discount rate | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.217
Discount rate | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.090
Discount rate | Interest in MSRs | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.095
Discount rate | Interest in MSRs | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.114
Discount rate | Interest in MSRs | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.100
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.090	0.090
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.120	0.120
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.090	0.094
Prepayment rate | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.067
Prepayment rate | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.144
Prepayment rate | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.075
Prepayment rate | Interest in MSRs | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.048
Prepayment rate | Interest in MSRs | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.146
Prepayment rate | Interest in MSRs | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.090
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.094	0.193
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.307	0.555
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.202	0.420
Delinquency rate | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.009
Delinquency rate | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.018
Delinquency rate | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.011
Delinquency rate | Interest in MSRs | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.006
Delinquency rate | Interest in MSRs | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.050
Delinquency rate | Interest in MSRs | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.018
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.000	0.000
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.060	0.060
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
MSR measurement inputs	0.024	0.025

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- Definition

Fair value inputs cost to service.

+ References

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- Definition

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- Definition

Value of input used to measure servicing asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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