LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Non-Accrual Details
Loans, net of unearned income	$ 674,909	$ 667,034
Loans at fair value	4,239	4,374
Corporate
Non-Accrual Details
Past due and accruing	968	735
Total non-accrual	1,540	1,942
Total current	342,714	326,352
Loans, net of unearned income	349,440	333,378
Loans at fair value	$ 4,218	4,349
Number of days past due, non-accrual status	90 days
Loans less than this number of days past due are considered current	30 days
Corporate \| Commercial and industrial
Non-Accrual Details
Past due and accruing	$ 460	262
Total non-accrual	1,123	1,506
Total current	145,612	139,554
Loans, net of unearned income	147,195	141,322
Corporate \| Financial institutions
Non-Accrual Details
Past due and accruing	155	108
Total non-accrual	74	92
Total current	82,299	73,557
Loans, net of unearned income	82,528	73,757
Corporate \| Mortgage and real estate
Non-Accrual Details
Past due and accruing	214	206
Total non-accrual	258	195
Total current	54,492	51,563
Loans, net of unearned income	54,964	51,964
Corporate \| Leases
Non-Accrual Details
Past due and accruing	19	76
Total non-accrual	0	46
Total current	1,557	1,533
Loans, net of unearned income	1,576	1,655
Corporate \| Other
Non-Accrual Details
Past due and accruing	120	83
Total non-accrual	85	103
Total current	58,754	60,145
Loans, net of unearned income	58,959	60,331
Corporate \| 30 to 89 Days Past Due
Non-Accrual Details
Past due and accruing	880	627
Corporate \| 30 to 89 Days Past Due \| Commercial and industrial
Non-Accrual Details
Past due and accruing	430	249
Corporate \| 30 to 89 Days Past Due \| Financial institutions
Non-Accrual Details
Past due and accruing	146	93
Corporate \| 30 to 89 Days Past Due \| Mortgage and real estate
Non-Accrual Details
Past due and accruing	209	147
Corporate \| 30 to 89 Days Past Due \| Leases
Non-Accrual Details
Past due and accruing	16	68
Corporate \| 30 to 89 Days Past Due \| Other
Non-Accrual Details
Past due and accruing	79	70
Corporate \| Equal to greater than 90 days past due and accruing
Non-Accrual Details
Past due and accruing	88	108
Corporate \| Equal to greater than 90 days past due and accruing \| Commercial and industrial
Non-Accrual Details
Past due and accruing	30	13
Corporate \| Equal to greater than 90 days past due and accruing \| Financial institutions
Non-Accrual Details
Past due and accruing	9	15
Corporate \| Equal to greater than 90 days past due and accruing \| Mortgage and real estate
Non-Accrual Details
Past due and accruing	5	59
Corporate \| Equal to greater than 90 days past due and accruing \| Leases
Non-Accrual Details
Past due and accruing	3	8
Corporate \| Equal to greater than 90 days past due and accruing \| Other
Non-Accrual Details
Past due and accruing	$ 41	$ 13

Financing Receivable, Recorded Investment, Past Due And Accruing

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- Definition

Represents the number of days past due the loan is less than for consideration as current. Loans 30 or more days past due are not considered current.

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Represents the number of days, the loan is past due for classifying as non-accrual.

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Financing receivables that are current.

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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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