Fair Value Of Financial Instruments (Schedule Of Fair Value Of Investments In And Unfunded Commitments To Funds Measured At Net Asset Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	$ 90,809	$ 167,353
Unfunded commitments	12,368	25,548
Private Company Investments [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	18,763	34,385
Unfunded commitments	8,526	14,178
Partnership Interests [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	15,798	22,502
Unfunded commitments	1,822	2,018
Mutual Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	11,301	20,399
Private Equity Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	9,310	12,970
Unfunded commitments	2,020	9,352
Money Market Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair value of investments	$ 35,637	$ 77,097

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.

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

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

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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