INVESTMENTS - Alternative Investment Funds (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Investments in Alternative Investment Funds
Alternative investment funds, fair value	$ 970,000,000	$ 1,839,000,000
Alternative investment funds, unfunded commitments	229,000,000	206,000,000
Amount of fund assets valued using net asset values provided by third party asset managers which is included in the total fair value amount of alternative investment funds	800,000,000	1,600,000,000
Hedge funds
Investments in Alternative Investment Funds
Alternative investment funds, fair value	8,000,000	751,000,000
Alternative investment funds, unfunded commitments	0	0
Alternative investment funds, redemption frequency (if currently eligible)	Generally quarterly
Hedge funds \| Minimum
Investments in Alternative Investment Funds
Alternative investment funds, redemption notice period	10 days
Hedge funds \| Maximum
Investments in Alternative Investment Funds
Alternative investment funds, redemption notice period	95 days
Private equity funds
Investments in Alternative Investment Funds
Alternative investment funds, fair value	796,000,000	794,000,000
Alternative investment funds, unfunded commitments	205,000,000	170,000,000
Real estate funds
Investments in Alternative Investment Funds
Alternative investment funds, fair value	166,000,000	294,000,000
Alternative investment funds, unfunded commitments	$ 24,000,000	$ 36,000,000

Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Notice Period

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- Definition

The amount of fund assets that are valued using NAV (net asset value) provided by third party asset managers is included in total alternative investment fund fair value.

+ References

No definition available.

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Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- Definition

States the frequency (for example, annually, semi-annually, quarterly) with which the entity can redeem its investment, or portion thereof, for each of those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments), by major category.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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