NON-CONSOLIDATED VARIABLE INTEREST ENTITIES AND SERVICING ASSETS - Weighted-Averages of Key Economic Assumptions in Valuation Model (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Transfers and Servicing [Abstract]
Carrying amount of servicing assets	$ 33,344	$ 26,762	$ 26,040	$ 26,874	$ 27,231	$ 27,428
Fair value	$ 37,757	$ 31,027
Weighted-average expected life	7 years 11 months 15 days	8 years 4 months 20 days
Constant prepayment rate	6.80%	6.45%
Decrease in fair value due to 10% adverse change, constant prepayment rate	$ 909	$ 748
Decrease in fair value due to 20% adverse change, constant prepayment rate	$ 1,782	$ 1,464
Discount rate	11.21%	11.27%
Decrease in fair value due to 10% adverse change, discount rate	$ 1,654	$ 1,450
Decrease in fair value due to 20% adverse change, discount rate	$ 3,182	$ 2,783

The hypothetical financial impact of a 10 percent adverse change of the discount rate on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

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The hypothetical financial impact of a 10 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

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The hypothetical financial impact of a 20 percent adverse change of the discount rate on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

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The hypothetical financial impact of a 20 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

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- Definition

Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

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Weighted average life of financial assets and financial liabilities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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