FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets
Securities available for sale	$ 18,656us-gaap_AvailableForSaleSecurities	$ 15,995us-gaap_AvailableForSaleSecurities
Loans held for sale	256	176
Derivative assets (related party balances of $1 and $0, respectively)	629us-gaap_DerivativeAssets	650us-gaap_DerivativeAssets
Liabilities
Derivative liabilities	612us-gaap_DerivativeLiabilities	939us-gaap_DerivativeLiabilities
Fair Value Measurement [Domain]
Assets
Securities available for sale	18,656	15,995
Loans held for sale	256
Derivative assets (related party balances of $1 and $0, respectively)	790	778
Venture capital investments and other investments	5	5
Total assets	19,707	16,954
Liabilities
Derivative liabilities	773	1,067
Total liabilities	773	1,067
Fair Value Measurement [Domain] \| Interest rate swaps
Assets
Derivative assets (related party balances of $1 and $0, respectively)	613	677
Liabilities
Derivative liabilities	600	970
Fair Value Measurement [Domain] \| Foreign exchange contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	170	94
Liabilities
Derivative liabilities	164	87
Fair Value Measurement [Domain] \| Other contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	7	7
Liabilities
Derivative liabilities	9	10
Fair Value Measurement [Domain] \| Mortgage-backed securities
Assets
Securities available for sale	18,606	15,945
Fair Value Measurement [Domain] \| State and political subdivisions
Assets
Securities available for sale	10	10
Fair Value Measurement [Domain] \| Equity securities
Assets
Securities available for sale	25	25
Fair Value Measurement [Domain] \| U.S. Treasury
Assets
Securities available for sale	15	15
Fair Value Measurement [Domain] \| Residential loans held for sale
Assets
Loans held for sale	213	176
Fair Value Measurement [Domain] \| Commercial real estate loans held for sale
Assets
Loans held for sale	43
Fair Value Measurement [Domain] \| Level 1
Assets
Securities available for sale	23	23
Loans held for sale	0
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Venture capital investments and other investments	0	0
Total assets	23	23
Liabilities
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value Measurement [Domain] \| Level 1 \| Interest rate swaps
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 1 \| Foreign exchange contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 1 \| Other contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 1 \| Mortgage-backed securities
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 1 \| State and political subdivisions
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 1 \| Equity securities
Assets
Securities available for sale	8	8
Fair Value Measurement [Domain] \| Level 1 \| U.S. Treasury
Assets
Securities available for sale	15	15
Fair Value Measurement [Domain] \| Level 1 \| Residential loans held for sale
Assets
Loans held for sale	0	0
Fair Value Measurement [Domain] \| Level 1 \| Commercial real estate loans held for sale
Assets
Loans held for sale	0
Fair Value Measurement [Domain] \| Level 2
Assets
Securities available for sale	18,633	15,972
Loans held for sale	256
Derivative assets (related party balances of $1 and $0, respectively)	790	778
Venture capital investments and other investments	0	0
Total assets	19,679	16,926
Liabilities
Derivative liabilities	773	1,067
Total liabilities	773	1,067
Fair Value Measurement [Domain] \| Level 2 \| Interest rate swaps
Assets
Derivative assets (related party balances of $1 and $0, respectively)	613	677
Liabilities
Derivative liabilities	600	970
Fair Value Measurement [Domain] \| Level 2 \| Foreign exchange contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	170	94
Liabilities
Derivative liabilities	164	87
Fair Value Measurement [Domain] \| Level 2 \| Other contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	7	7
Liabilities
Derivative liabilities	9	10
Fair Value Measurement [Domain] \| Level 2 \| Mortgage-backed securities
Assets
Securities available for sale	18,606	15,945
Fair Value Measurement [Domain] \| Level 2 \| State and political subdivisions
Assets
Securities available for sale	10	10
Fair Value Measurement [Domain] \| Level 2 \| Equity securities
Assets
Securities available for sale	17	17
Fair Value Measurement [Domain] \| Level 2 \| U.S. Treasury
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 2 \| Residential loans held for sale
Assets
Loans held for sale	213	176
Fair Value Measurement [Domain] \| Level 2 \| Commercial real estate loans held for sale
Assets
Loans held for sale	43
Fair Value Measurement [Domain] \| Level 3
Assets
Securities available for sale	0	0
Loans held for sale	0
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Venture capital investments and other investments	5	5
Total assets	5	5
Liabilities
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value Measurement [Domain] \| Level 3 \| Interest rate swaps
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 3 \| Foreign exchange contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 3 \| Other contracts
Assets
Derivative assets (related party balances of $1 and $0, respectively)	0	0
Liabilities
Derivative liabilities	0	0
Fair Value Measurement [Domain] \| Level 3 \| Mortgage-backed securities
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 3 \| State and political subdivisions
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 3 \| Equity securities
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 3 \| U.S. Treasury
Assets
Securities available for sale	0	0
Fair Value Measurement [Domain] \| Level 3 \| Residential loans held for sale
Assets
Loans held for sale	0	0
Fair Value Measurement [Domain] \| Level 3 \| Commercial real estate loans held for sale
Assets
Loans held for sale	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Publisher FASB

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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- Definition

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

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