Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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Investment Securities (Debt securities issued by corporation) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	$ 2,541.6	$ 2,746.0	$ 2,534.6	$ 2,328.7
Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fixed maturity investments, at fair value	486.7	467.2
Fair value investments	486.7	467.2
AAA \| Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	11.3	9.5
AA \| Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	63.6	73.9
A \| Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	304.7	288.5
BBB \| Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	106.1	95.3
BB \| Debt securities issued by corporations
Debt and Equity Securities, FV-NI [Line Items]
Fair value investments	$ 1.0	$ 0.0