FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity, carrying value	$ 3,319	$ 4,165
Securities held-to-maturity, fair value	3,362	4,041
Equity securities, at cost, carrying value	734	834
Equity securities, at cost, fair value	734	834
Other loans held for sale, carrying value	22	101
Other loans held for sale, fair value	22	101
Loans and leases, carrying value	117,880	116,660
Loans and leases, fair value	118,961	116,627
Deposits, carrying value	124,714	119,575
Deposits, fair value	124,852	119,503
Federal funds purchased and securities sold under agreements to repurchase, carrying value	867	1,156
Federal funds purchased and securities sold under agreements to repurchase, fair value	867	1,156
Other short-term borrowed funds, carrying value	210	161
Other short-term borrowed funds, fair value	210	161
Long-term borrowed funds, carrying value	12,806	15,925
Long-term borrowed funds, fair value	12,952	15,877
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity, carrying value	0	0
Securities held-to-maturity, fair value	0	0
Equity securities, at cost, carrying value	0	0
Equity securities, at cost, fair value	0	0
Other loans held for sale, carrying value	0	0
Other loans held for sale, fair value	0	0
Loans and leases, carrying value	0	0
Loans and leases, fair value	0	0
Deposits, carrying value	0	0
Deposits, fair value	0	0
Federal funds purchased and securities sold under agreements to repurchase, carrying value	0	0
Federal funds purchased and securities sold under agreements to repurchase, fair value	0	0
Other short-term borrowed funds, carrying value	0	0
Other short-term borrowed funds, fair value	0	0
Long-term borrowed funds, carrying value	0	0
Long-term borrowed funds, fair value	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity, carrying value	3,319	4,165
Securities held-to-maturity, fair value	3,362	4,041
Equity securities, at cost, carrying value	734	834
Equity securities, at cost, fair value	734	834
Other loans held for sale, carrying value	0	0
Other loans held for sale, fair value	0	0
Loans and leases, carrying value	332	338
Loans and leases, fair value	332	338
Deposits, carrying value	124,714	119,575
Deposits, fair value	124,852	119,503
Federal funds purchased and securities sold under agreements to repurchase, carrying value	867	1,156
Federal funds purchased and securities sold under agreements to repurchase, fair value	867	1,156
Other short-term borrowed funds, carrying value	210	161
Other short-term borrowed funds, fair value	210	161
Long-term borrowed funds, carrying value	12,806	15,925
Long-term borrowed funds, fair value	12,952	15,877
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity, carrying value	0	0
Securities held-to-maturity, fair value	0	0
Equity securities, at cost, carrying value	0	0
Equity securities, at cost, fair value	0	0
Other loans held for sale, carrying value	22	101
Other loans held for sale, fair value	22	101
Loans and leases, carrying value	117,548	116,322
Loans and leases, fair value	118,629	116,289
Deposits, carrying value	0	0
Deposits, fair value	0	0
Federal funds purchased and securities sold under agreements to repurchase, carrying value	0	0
Federal funds purchased and securities sold under agreements to repurchase, fair value	0	0
Other short-term borrowed funds, carrying value	0	0
Other short-term borrowed funds, fair value	0	0
Long-term borrowed funds, carrying value	0	0
Long-term borrowed funds, fair value	$ 0	$ 0

The amount of other loans receivable that will be sold to other entities.

No definition available.

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- Definition

Fair value portion of other loans receivable held-for-sale.

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Fair value portion of short-term borrowings not otherwise specified in the taxonomy having initial terms less than one year or the normal operating cycle, if longer.

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Total Other Investment Securities At Cost, Amortized Cost Basis

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Total Other Investment Securities At Cost, Fair Value

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03.12)
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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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No definition available.

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Amount after offset of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. 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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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

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