Fair Value Disclosures (Fair Value of Equity Fund and Hedge Fund) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value of Investments that Calculate Net Asset Value
Fair Value, Investments	$ 4,278	$ 5,009
Private Equity Funds
Fair Value of Investments that Calculate Net Asset Value
Fair value of investment to be liquidated (less than 5 years)	139
Fair value of investment to be liquidated (5-10 years)	1,151
Fair value of investment to be liquidated (Over 10 years)	672
Fair Value, Investments	1,962	2,569
Real Estate Funds
Fair Value of Investments that Calculate Net Asset Value
Fair value of investment to be liquidated (less than 5 years)	235
Fair value of investment to be liquidated (5-10 years)	882
Fair value of investment to be liquidated (Over 10 years)	547
Fair Value, Investments	1,664	1,753
Long-short Equity Hedge Funds
Fair Value of Investments that Calculate Net Asset Value
Fair Value, Investments	$ 447	433
Long-short Equity Hedge Funds \| Initial Period Lock-up Restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	1.00%
Long-short Equity Hedge Funds \| Gate restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	12.00%
Fixed Income Funds
Fair Value of Investments that Calculate Net Asset Value
Fair Value, Investments	$ 73	76
Fixed Income Funds \| Initial Period Lock-up Restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	13.00%
Event Driven Hedge Funds
Fair Value of Investments that Calculate Net Asset Value
Fair Value, Investments	$ 3	39
Event Driven Hedge Funds \| Initial Period Lock-up Restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	3.00%
Multi-strategy Hedge Funds
Fair Value of Investments that Calculate Net Asset Value
Fair Value, Investments	$ 129	$ 139
Multi-strategy Hedge Funds \| Initial Period Lock-up Restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	37.00%
Multi-strategy Hedge Funds \| Gate restrictions
Fair Value of Investments that Calculate Net Asset Value
Percent of investments that cannot be redeemed currently	28.00%

Fair value of investments that will be liquidated after ten years.

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- Definition

Fair value of investments that will be liquidated within five to ten years.

+ References

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- Definition

Fair value of investments that will be liquidated in the next five years.

+ References

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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 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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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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The percentage of the total value of investments that cannot be redeemed because of a redemption restriction as of the statement of financial position date.

+ References

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