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Investment Securities - Other long-term investments (Details) - USD ($) $ in Millions | Jun. 30, 2022 | Dec. 31, 2021
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Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | $ 1,468.7 | $ 1,377.8
Asset Management (Kudu) |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 727.0 | 669.5
PassportCard/DavidShield |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 132.0 | 120.0
Elementum Holdings, L.P. |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 45.0 | 45.0
Other unconsolidated entities |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 12.2 | 34.4
Total unconsolidated entities |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 916.2 | 868.9
Private equity funds and hedge funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 200.1 | 153.8
Bank loan fund |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 154.4 | 163.0
Lloyd’s trust deposits |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 113.4 | 113.8
ILS funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 51.6 | 51.9
Private debt investments |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | 13.0 | 14.1
Other |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total other long-term investments | $ 20.0 | $ 12.3

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- Definition Amount of long-term 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 -Subparagraph (SX 210.7-03.1(f)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(12)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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