ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Summary of Allowance for Credit Losses by Evaluation Method (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	$ 99	$ 64
Formula-based evaluation	1,209	1,269
Allowance for credit losses	1,308	1,333
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	74	38
Formula-based evaluation	683	743
Allowance for credit losses	757	781
Retail
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	25	26
Formula-based evaluation	526	526
Allowance for credit losses	$ 551	$ 552

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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- Definition

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No definition available.

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