Business Segments - Segment Operating Profit (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
Segment Reporting Information [Line Items]
Operating Income (Loss)									$ 84.5	$ 136.3	$ 229.2
Net Realized Gains on Sales of Investments	$ 9.4	$ 5.3	$ 34.0	$ 3.4	$ 21.0	$ 8.0	$ 3.5	$ 6.6	52.1	39.1	99.1
Net Impairment Losses Recognized in Earnings	(14.7)	(3.3)	(2.2)	(7.0)	(6.5)	(3.8)	(4.1)	(0.8)	(27.2)	(15.2)	(13.9)
Loss from Early Extinguishment of Debt	0.0	0.0	0.0	9.1					9.1	0.0	0.0
Income from Continuing Operations before Income Taxes	$ (1.6)	$ 49.8	$ 34.3	$ 17.8	$ 93.1	$ 4.0	$ 11.2	$ 51.9	100.3	160.2	314.4
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									133.4	169.0	276.5
Operating Segments [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									23.7	27.1	139.6
Operating Segments [Member] | Life and Health Insurance [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									109.7	141.9	136.9
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									(48.9)	(32.7)	(47.3)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net Realized Gains on Sales of Investments									52.1	39.1	99.1
Net Impairment Losses Recognized in Earnings									(27.2)	(15.2)	(13.9)
Loss from Early Extinguishment of Debt									$ (9.1)	$ 0.0	$ 0.0