Business Segments - Amortization of Deferred Policy Acquisitions Costs By Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Amortization of Deferred Policy Acquisition Costs	$ 257.4	$ 235.4	$ 253.9
Operating Segments [Member]
Segment Reporting Information [Line Items]
Amortization of Deferred Policy Acquisition Costs	257.4	235.4	253.9
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Amortization of Deferred Policy Acquisition Costs	213.1	187.5	207.2
Life and Health Insurance [Member]
Segment Reporting Information [Line Items]
Amortization of Deferred Policy Acquisition Costs	$ 44.3	$ 47.9	$ 46.7