Fair Value Measurement - Investments in LLCs and Limited Partnerships Footnote (Details)	12 Months Ended
Dec. 31, 2016 fund
Private debt funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Number of unrelated LPs funds	2
Number of LPs to allow redemption by special consent	1
Private debt funds \| Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Anticipated time frame for distribution at the discretion of the LP (years)	3 years
Private debt funds \| Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Anticipated time frame for distribution at the discretion of the LP (years)	8 years
Long equity fund
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Entities that calculate net asset value notice period (years)	15 days
Payment period for redemption of LP valued at NAV (years)	10 days
Long/short equity funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Payment period for redemption of LP valued at NAV (years)	30 days
Redemption percentage of LP at NAV for which initial payment is limited (percent)	90.00%
Long/short equity funds \| Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Entities that calculate net asset value notice period (years)	30 days
Long/short equity funds \| Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Entities that calculate net asset value notice period (years)	90 days
Non-public equity funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Anticipated time frame for distribution at the discretion of the LP (years)	9 years
Structured credit fund
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Entities that calculate net asset value notice period (years)	90 days
Long/short commodities fund
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Entities that calculate net asset value notice period (years)	30 days
Lock-up period (in years)	1 year
Payment period for redemption of LP valued at NAV (years)	30 days

Number of Limited Partners to Allow Redemption by Special Consent

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- Definition

Number of Unrelated Limited Partnership Funds

+ References

No definition available.

+ Details

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- Definition

The number of days required for payment upon redemption of a particular LP that is valued at NAV.

+ References

No definition available.

+ Details

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- Definition

The redemption percentage of a particular LP valued at NAV above which initial payment is limited.

+ References

No definition available.

+ Details

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- Definition

Notice period the entity is required to deliver before it can redeem an investment calculated using net asset value per share, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, investments calculated by per unit, per membership interest, other equity or ownership interest and 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 (d)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258

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- Definition

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.

+ References

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- Definition

Estimate remaining period the underlying assets are expected to be liquidated by the investees for investments for which net asset value per share is calculated (including by unit, membership interest, or other ownership interest unit measure), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258

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- Definition

Remaining period of a redemption restriction related to investments for which net asset value per share is calculated, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (e)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258

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