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Fair Value Measurements - Investments Measured at Net Asset Value as Practical Expedient (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2017 | Dec. 31, 2016
NAV of investments at fair value |  |  |
Life of funds (in years) |  | 15 years |
Other Investments |  |  |
NAV of investments at fair value |  |  |
Fair Value | [1] | $ 160.5 | $ 147.5
Unfunded Commitments |  | 94.9 | 92.2
Other Investments | Controlling Interest |  |  |
NAV of investments at fair value |  |  |
Fair Value |  | 59.9 | 72.8
Private Equity Funds |  |  |
NAV of investments at fair value |  |  |
Fair Value | [2] | 151.9 | 137.8
Unfunded Commitments | [2] | 94.9 | 92.2
Other Funds |  |  |
NAV of investments at fair value |  |  |
Fair Value | [3] | 8.6 | 9.7
Unfunded Commitments | [3] | $ 0.0 | $ 0.0
[1] | Fair value attributable to the controlling interest was $59.9 million and $72.8 million as of December 31, 2016 and September 30, 2017, respectively.
[2] | The Company uses NAV as a practical expedient one quarter in arrears (adjusted for current period calls and distributions) to determine the fair value. 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.
[3] | 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.

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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 6A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258 + Details
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