ALLOWANCE FOR CREDIT LOSSES - Allowance for Loan Losses Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for credit losses
Allowance for loan losses at beginning of period	$ 12,355	$ 12,060	$ 12,626
Gross credit losses	(8,665)	(8,673)	(8,222)
Gross recoveries	1,552	1,597	1,661
Net credit losses (NCLs)	(7,113)	(7,076)	(6,561)
NCLs	7,113	7,076	6,561
Net reserve builds (releases)	394	544	340
Net specific reserve releases	(153)	(117)	(152)
Total provision for loan losses	7,354	7,503	6,749
Other	(281)	(132)	(754)
Allowance for loan losses at the end of year	12,315	12,355	12,060
Allowance for credit losses on unfunded lending commitments
Allowance for credit losses on unfunded lending commitments at beginning of period	1,258	1,418	1,402
Provision (release) for unfunded lending commitments	113	(161)	29
Other, net	(4)	1	(13)
Allowance for credit losses on unfunded lending commitments at end of period	1,367	1,258	1,418
Total allowance for loans, leases and unfunded lending commitments	13,682	13,613	13,478
Sales or transfers of various consumer loan portfolios to held-for-sale
Other	(281)	(132)	(754)
Consumer
Sales or transfers of various consumer loan portfolios to held-for-sale
Transfer of real estate loan portfolios	(91)	(106)	(106)
Transfer of other loan portfolios	(110)	(155)	(468)
Sales or transfers of various consumer loan portfolios to HFS	(201)	(261)	(574)
FX translation, consumer	(60)	115	(199)
Corporate
Allowance for credit losses
Other	(20)	14	19
Sales or transfers of various consumer loan portfolios to held-for-sale
Other	$ (20)	$ 14	$ 19

Allowance For Loan And Lease Losses, Loans Transferred To Other Loan Portfolios

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- Definition

Allowance For Loan And Lease Losses, Loans Transferred To Real Estate Loan Portfolio

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No definition available.

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- Definition

The reserve to cover probable credit losses related to loans and leases receivable and unfunded lending commitments as of the balance sheet date.

+ References

No definition available.

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Provision charged or released during the period against earnings for unfunded lending commitments other net.

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Provision charged or released during the period against earnings for credit losses on loans and leases receivable that are expected and were collectively evaluated for impairment.

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No definition available.

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Provision charged or released during the period against earnings for credit losses on loans and leases receivable that are expected and were individually evaluated for impairment.

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The reserve to cover probable credit losses related to unfunded lending commitments as of the balance sheet date.

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No definition available.

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Unfunded Lending Commitments Allowance For Credit Losses, Adjustments, Net

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of other addition (reduction) in allowance reserve for credit loss.

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Amount of gain (loss) from converting allowance reserve for credit loss to currency of reporting entity from amount denominated or measured in a different currency, which decreases (increases) the allowance for loan and lease losses.

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Amount of reduction of allowance reserve for credit loss arising from sale of loan and lease portfolios.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount, after recoveries, of loans and leases that have been written-off.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to loss from loan transactions.

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