Investment securities - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Net Investment Income
Total investment income	$ 23.8	$ 13.1
Investment expenses	(3.7)	(2.3)
Net investment income	20.1	10.8
Fixed maturity investments
Net Investment Income
Total investment income	16.8	9.9
Short-term investments
Net Investment Income
Total investment income	0.4	0.8
Equity securities
Net Investment Income
Total investment income	2.7	1.2
Other long-term investments
Net Investment Income
Total investment income	$ 3.9	$ 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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-SubTopic 220
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Amount of expenses related to the generation of investment income.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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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