Business Segments - Earned Premiums by Product Line (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Life									$ 387.6	$ 392.7	$ 393.4
Premiums Earned, Net, Accident and Health									148.6	161.4	165.2
Earned Premiums	451.5	462.8	470.3	477.6	495.6	507.5	512.8	509.9	1,862.2	2,025.8	2,107.1
Personal Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									831.4	959.1	1,050.1
Homeowners [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									312.4	326.2	318.0
Other Personal Lines [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									127.4	134.1	136.9
Commercial Automobile [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Premiums Earned, Net, Property and Casualty									$ 54.8	$ 52.3	$ 43.5