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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 | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 USD ($) | Dec. 31, 2020 USD ($)
Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | $ 92 |
Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | 103 |
Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | 98 |
Interest in MSRs | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | 78 |
Interest in MSRs | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | 84 |
Interest in MSRs | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service | $ 81 |
Consolidated VIEs | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service |  | $ 83
Consolidated VIEs | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service |  | 108
Consolidated VIEs | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Cost to service |  | $ 98
Discount rate | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.030 |
Discount rate | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.126 |
Discount rate | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.077 |
Discount rate | Interest in MSRs | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.075 |
Discount rate | Interest in MSRs | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.090 |
Discount rate | Interest in MSRs | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.079 |
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.090
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.120
Discount rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.094
Prepayment rate | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.069 |
Prepayment rate | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.178 |
Prepayment rate | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.090 |
Prepayment rate | Interest in MSRs | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.051 |
Prepayment rate | Interest in MSRs | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.159 |
Prepayment rate | Interest in MSRs | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.096 |
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.193
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.555
Prepayment rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 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 | 0.014 |
Delinquency rate | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.010 |
Delinquency rate | Interest in MSRs | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.000 |
Delinquency rate | Interest in MSRs | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.002 |
Delinquency rate | Interest in MSRs | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs | 0.001 |
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Minimum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.000
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Maximum |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.060
Delinquency rate | Consolidated VIEs | Mortgage Servicing Rights | Weighted Average |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
MSR measurement inputs |  | 0.025

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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 + Details
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