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Fair Value Measurements - Nature of Investments and Related Liquidity (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
NAV of investments at fair value |  |  |
Life of funds (in years) |  | 15 years |
Private equity |  |  |
NAV of investments at fair value |  |  |
Fair Value | [1] | $ 156.1 | $ 137.8
Unfunded Commitments | [1] | 98.8 | 92.2
Other funds |  |  |
NAV of investments at fair value |  |  |
Fair Value | [2] | 8.9 | 9.7
Unfunded Commitments | [2] | 0.0 | 0.0
Other investments |  |  |
NAV of investments at fair value |  |  |
Fair Value | [3] | 165.0 | 147.5
Unfunded Commitments | [3] | 98.8 | 92.2
Other investments | Parent |  |  |
NAV of investments at fair value |  |  |
Fair Value |  | $ 80.1 | $ 59.9
[1] | These funds primarily invest in a broad range of private equity funds, as well as making direct investments. Distributions will be received as the underlying assets are liquidated over the life of the funds, which is generally up to 15 years.
[2] | These are multi-disciplinary funds that invest across various asset classes and strategies, including long/short equity, credit and real estate. Investments are generally redeemable on a daily, monthly or quarterly basis.
[3] | Fair value attributable to the controlling interest was $59.9 million and $80.1 million as of December 31, 2016 and 2017, respectively.

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- Definition Fair value of investment in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes measurement of net asset value as estimate of fair value. + 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 (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258 + Details
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