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Fair Value Measurements - Nature of Investments and Related Liquidity (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
NAV of investments at fair value |  |  |
Life of funds (in years) |  | 15 years |
Private equity |  |  |
NAV of investments at fair value |  |  |
Unfunded Commitments | [1] | $ 127.2 | $ 131.0
Other funds |  |  |
NAV of investments at fair value |  |  |
Unfunded Commitments | [2] | 0.0 | 0.0
Other investments |  |  |
NAV of investments at fair value |  |  |
Unfunded Commitments | [3] | 127.2 | 131.0
Other investments | Controlling interests |  |  |
NAV of investments at fair value |  |  |
Alternative Investment |  | 137.6 | 123.2
Fair Value Measured at NAV | Private equity |  |  |
NAV of investments at fair value |  |  |
Alternative Investment | [1] | 203.3 | 193.2
Fair Value Measured at NAV | Other funds |  |  |
NAV of investments at fair value |  |  |
Alternative Investment | [2] | 8.5 | 7.9
Fair Value Measured at NAV | Other investments |  |  |
NAV of investments at fair value |  |  |
Alternative Investment | [3] | $ 211.8 | $ 201.1
[1] | 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 third-party funds and 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 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 $123.2 million and $137.6 million as of December 31, 2018 and 2019, respectively.

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- Definition Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 35 -Paragraph 54B -URI http://asc.fasb.org/extlink&oid=117332851&loc=SL7495116-110257 + Details
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