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Investment Securities - Other Long-Term Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Investment securities
Other investments	$ 786.8	$ 676.3
Kudu
Investment securities
Other investments	400.6	266.5
PassportCard/DavidShield
Investment securities
Other investments	95.0	90.0
Elementum
Investment securities
Other investments	55.1	55.1
Other unconsolidated entities
Investment securities
Other investments	42.4	33.7
Unconsolidated entities
Investment securities
Other investments	593.1	445.3
Private equity funds and hedge funds
Investment securities
Other investments	121.2	161.1
Insurance-linked securities funds
Investment securities
Other investments	51.4	41.2
Private debt investments
Investment securities
Other investments	21.1	28.7
Private debt instruments
Investment securities
Alternative investment	$ 5.8	$ 5.0

X

- 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)
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-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

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- Definition

Amount of investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

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+ References

No definition available.

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