Fair Value Measurements - Investments in Company-Sponsored Funds (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Investment Holdings [Line Items]
Fair Value	$ 6,605
Unfunded Commitments	$ 1,400
Hedge Funds [Member]
Investment Holdings [Line Items]
Investment Redemption Notice Period Minimum	30 days
Investment Redemption Notice Period Maximum	120 days
Fair Value	$ 1,631
Unfunded Commitments	$ 0
Redemption Frequency	Annually
Private Equity Funds
Investment Holdings [Line Items]
Investments Lock In Period	10 years
Fair Value	$ 4,974
Unfunded Commitments	$ 1,400

Investment redemption frequency.

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- Definition

Investment redemption notice period maximum.

+ References

No definition available.

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- Definition

Investment redemption notice period minimum.

+ References

No definition available.

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- Definition

Investments lock in period.

+ References

No definition available.

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=99377789&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

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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