Business Segments - Earned Premiums by Product Line (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Entity-Wide Information, Revenue from External Customer [Line Items]
Earned Premiums, Life	$ 94.4	$ 88.0
Earned Premiums, Accident and Health	36.9	36.8
Earned Premiums, Total	546.0	431.3
Personal Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Earned Premiums, Property and Casualty	303.3	189.8
Homeowners [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Earned Premiums, Property and Casualty	68.1	72.6
Other Personal Property and Casualty Insurance [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Earned Premiums, Property and Casualty	29.8	30.6
Commercial Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Earned Premiums, Property and Casualty	$ 13.5	$ 13.5