Business Segments - Earned Premiums by Product Line (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Life									$ 374.1	$ 387.6	$ 392.7
Premiums Earned, Net, Accident and Health									144.9	148.6	161.4
Earned Premiums	$ 541.5	$ 536.7	$ 500.1	$ 431.3	$ 451.5	$ 462.8	$ 470.3	$ 477.6	2,009.6	1,862.2	2,025.8
Personal Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									1,027.7	831.4	959.1
Homeowners [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									286.3	312.4	326.2
Other Personal Lines [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									122.1	127.4	134.1
Commercial Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									$ 54.5	$ 54.8	$ 52.3