Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Net Investment Income [Line Items]
Gross investment income	$ 52.3	$ 51.3
External investment expense	(0.4)	(0.2)
Net investment income	51.9	51.1
Total fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	45.6	43.6
Equity securities
Net Investment Income [Line Items]
Gross investment income	1.0	2.5
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	5.4	3.7
Policy loans
Net Investment Income [Line Items]
Gross investment income	0.3	0.3
Other invested assets
Net Investment Income [Line Items]
Gross investment income	$ 0.0	$ 1.2

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

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