FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity, carrying value	$ 5,567	$ 5,148
Securities held-to-maturity, fair value	5,611	5,193
Other investment securities, carrying value	866	872
Other investment securities, fair value	866	872
Other loans held for sale, carrying value	300	25
Other loans held for sale, fair value	300	25
Loans and leases, carrying value	96,538	93,410
Loans and leases, fair value	96,700	93,674
Deposits, carrying value	100,615	95,707
Deposits, fair value	100,620	95,710
Federal funds purchased and securities sold under agreements to repurchase, carrying value	3,784	4,276
Federal funds purchased and securities sold under agreements to repurchase, fair value	3,784	4,276
Other short-term borrowed funds, carrying value	6,762	6,253
Other short-term borrowed funds, fair value	6,762	6,253
Long-term borrowed funds, carrying value	3,890	4,642
Long-term borrowed funds, fair value	3,871	4,706
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
Other investment securities, carrying value	0	0
Other investment securities, 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	5,567	5,148
Securities held-to-maturity, fair value	5,611	5,193
Other investment securities, carrying value	866	872
Other investment securities, fair value	866	872
Other loans held for sale, carrying value	0	0
Other loans held for sale, fair value	0	0
Loans and leases, carrying value	87	102
Loans and leases, fair value	87	102
Deposits, carrying value	100,615	95,707
Deposits, fair value	100,620	95,710
Federal funds purchased and securities sold under agreements to repurchase, carrying value	3,784	4,276
Federal funds purchased and securities sold under agreements to repurchase, fair value	3,784	4,276
Other short-term borrowed funds, carrying value	6,762	6,253
Other short-term borrowed funds, fair value	6,762	6,253
Long-term borrowed funds, carrying value	3,890	4,642
Long-term borrowed funds, fair value	3,871	4,706
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
Other investment securities, carrying value	0	0
Other investment securities, fair value	0	0
Other loans held for sale, carrying value	300	25
Other loans held for sale, fair value	300	25
Loans and leases, carrying value	96,451	93,308
Loans and leases, fair value	96,613	93,572
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

Fair value of other investment securities.

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The amortized cost as of the balance sheet date of other investment securities.

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

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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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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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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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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 after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as 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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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. 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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Sum of the carrying amounts at the balance sheet date 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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