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Fair Value Measurement (Investments in LLCs and Limited Partnerships) (Details) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014
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Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships fair value | $ 162,624 | $ 133,250
Private debt funds [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 14,267 |
Investments in limited liability companies and limited partnerships fair value | 50,268 | 37,296
Long equity fund [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 0 |
Investments in limited liability companies and limited partnerships fair value | 6,407 | 6,747
Long/Short equity funds [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 0 |
Investments in limited liability companies and limited partnerships fair value | 28,030 | 25,301
Non-public equity funds [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 48,381 |
Investments in limited liability companies and limited partnerships fair value | 65,722 | 51,811
Multi-strategy fund of funds [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 0 |
Investments in limited liability companies and limited partnerships fair value | 8,252 | 8,271
Structured credit fund [Member] |  |
Investments in private funds [Abstract] |  |
Investments in limited liability companies and limited partnerships unfunded commitments | 0 |
Investments in limited liability companies and limited partnerships fair value | $ 3,945 | $ 3,824

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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 + Details
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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=36462937&loc=SL6742756-110258 + Details
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