INVESTMENTS - Recognition and Measurement of OTTI (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OTTI on Investments disclosures
Total OTTI losses recognized during the period	$ 26	$ 163
Less: Impairments recognized in AOCI	8	98	66
Net impairment losses recognized in earnings for securities that the Company does not intend to sell nor will likely be required to sell	18	65
Impairment losses recognized in earnings for securities that the Company intends to sell or more- likely-than-not will be required to sell before recovery	406	470
Net impairment losses recognized in earnings	424	535	4,971
MSSB
OTTI on Investments disclosures
Percentage of ownership interest held	35.00%
Securities available-for-sale (AFS)
OTTI on Investments disclosures
Total OTTI losses recognized during the period	21	9
Less: Impairments recognized in AOCI	8	0
Net impairment losses recognized in earnings for securities that the Company does not intend to sell nor will likely be required to sell	13	9
Impairment losses recognized in earnings for securities that the Company intends to sell or more- likely-than-not will be required to sell before recovery	380	269
Net impairment losses recognized in earnings	393	278
Held-to-maturity Securities
OTTI on Investments disclosures
Total OTTI losses recognized during the period	5	154
Less: Impairments recognized in AOCI	0	98
Net impairment losses recognized in earnings for securities that the Company does not intend to sell nor will likely be required to sell	5	56
Impairment losses recognized in earnings for securities that the Company intends to sell or more- likely-than-not will be required to sell before recovery	26	0
Net impairment losses recognized in earnings	31	56
Other assets
OTTI on Investments disclosures
Total OTTI losses recognized during the period	0	0
Less: Impairments recognized in AOCI	0	0
Net impairment losses recognized in earnings for securities that the Company does not intend to sell nor will likely be required to sell	0	0
Impairment losses recognized in earnings for securities that the Company intends to sell or more- likely-than-not will be required to sell before recovery	0	201
Net impairment losses recognized in earnings	$ 0	$ 201

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For investments that the entity does not intend to sell nor will likely be required to sell, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in earnings for securities (after net of the amount recognized in other comprehensive income).

+ References

No definition available.

+ Details

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- Definition

The aggregate amount (i) of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis and OTTI losses recognized during the period on investments accounted for under the cost method of accounting.; and (ii) of an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting.

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No definition available.

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- Definition

For investments that the entity does not intend to sell nor will likely be required to sell, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, prior to considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

No definition available.

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For investments that the entity does intend to sell or will more-likely-than-not be required to sell before recovery, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in earnings for securities.

+ References

No definition available.

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

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- Definition

Amount before tax of other than temporary impairment (OTTI) loss on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 35

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e25362-111560

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