INVESTMENTS - Alternative Investment Funds (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Investments in Alternative Investment Funds
Alternative investment funds, fair value	$ 408	$ 895
Alternative investment funds, unfunded commitments	102	194
Hedge funds
Investments in Alternative Investment Funds
Alternative investment funds, fair value	4	3
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 (in days)	10 days
Hedge funds \| Maximum
Investments in Alternative Investment Funds
Alternative investment funds, redemption notice period (in days)	95 days
Private equity
Investments in Alternative Investment Funds
Alternative investment funds, fair value	$ 348	762
Alternative investment funds, unfunded commitments	82	173
Real estate funds
Investments in Alternative Investment Funds
Alternative investment funds, fair value	56	130
Alternative investment funds, unfunded commitments	$ 20	$ 21

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

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- Definition

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 6A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&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=66048111&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=66048111&loc=SL6742756-110258

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- References

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