Fair Value of Financial Instruments Instruments Carried at NAV (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Instruments Carried at NAV [Abstract]
Fair value investments entities that calculate net asset value per share liquidating investment original expected lives increments	1 year
Unfunded commitment, private investment fund	$ 46.4	$ 63.8
Cash equivalents measured at NAV, which approximates fair value	29.5	58.7
Alternative Investment	$ 38.4	$ 16.2

Cash equivalents measured at net asset value.

No definition available.

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- Definition

Increments to average original expected period the underlying assets are expected to be liquidated by the investees for investments for which net asset value per share is calculated.

+ References

No definition available.

+ Details

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- Definition

Instruments Carried at NAV [Abstract]

+ References

No definition available.

+ Details

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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=123874694&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=122636397&loc=SL7495116-110257

+ 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258

+ Details

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