Investments (Aggregate Fair Value And Gross Unrealized Loss Of Fixed Maturity Securities And Equity Securities In An Unrealized Loss Position) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013 securities	Dec. 31, 2012 securities
Investment [Line Items]
Number of Securities, 12 Months or Less	3,451	1,709
Estimated Fair Value, 12 Months or Less	$ 6,636.9	$ 1,911.2
Gross Unrealized Losses, Less than 12 Months	(244.5)	(36.7)
Number of Securities, 12 Months or Greater	250	143
Estimated Fair Value, 12 Months or Greater	301.7	158.0
Gross Unrealized Losses, 12 Months or Greater	(33.3)	(14.6)
Fixed Maturity Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	3,025	748
Estimated Fair Value, 12 Months or Less	6,516.1	1,761.6
Gross Unrealized Losses, Less than 12 Months	(236.5)	(24.2)
Number of Securities, 12 Months or Greater	250	143
Estimated Fair Value, 12 Months or Greater	301.7	158.0
Gross Unrealized Losses, 12 Months or Greater	(33.3)	(14.6)
Fixed Maturity Securities [Member] | United States Government Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	27	17
Estimated Fair Value, 12 Months or Less	179.2	48.5
Gross Unrealized Losses, Less than 12 Months	(3.4)	(0.2)
Number of Securities, 12 Months or Greater	0	0
Estimated Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fixed Maturity Securities [Member] | Government Sponsored Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	22
Estimated Fair Value, 12 Months or Less	73.4
Gross Unrealized Losses, Less than 12 Months	(1.3)	0
Number of Securities, 12 Months or Greater	0
Estimated Fair Value, 12 Months or Greater	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fixed Maturity Securities [Member] | States, Municipalities And Political Subdivisions - Tax-Exempt [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	806	184
Estimated Fair Value, 12 Months or Less	2,070.9	420.1
Gross Unrealized Losses, Less than 12 Months	(90.1)	(5.7)
Number of Securities, 12 Months or Greater	42	1
Estimated Fair Value, 12 Months or Greater	82.4	46.9
Gross Unrealized Losses, 12 Months or Greater	(9.6)	(1.6)
Fixed Maturity Securities [Member] | Corporate Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	1,448	457
Estimated Fair Value, 12 Months or Less	2,586.6	1,066.5
Gross Unrealized Losses, Less than 12 Months	(95.2)	(17.0)
Number of Securities, 12 Months or Greater	107	74
Estimated Fair Value, 12 Months or Greater	81.3	52.6
Gross Unrealized Losses, 12 Months or Greater	(15.5)	(8.0)
Fixed Maturity Securities [Member] | Residential Mortgage-Backed Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	605	79
Estimated Fair Value, 12 Months or Less	1,243.0	211.0
Gross Unrealized Losses, Less than 12 Months	(41.4)	(1.1)
Number of Securities, 12 Months or Greater	80	44
Estimated Fair Value, 12 Months or Greater	116.2	25.5
Gross Unrealized Losses, 12 Months or Greater	(7.1)	(1.9)
Fixed Maturity Securities [Member] | Commercial Mortgage-Backed Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	52	4
Estimated Fair Value, 12 Months or Less	177.7	10.1
Gross Unrealized Losses, Less than 12 Months	(2.6)	0
Number of Securities, 12 Months or Greater	4	3
Estimated Fair Value, 12 Months or Greater	5.6	4.1
Gross Unrealized Losses, 12 Months or Greater	(0.3)	0
Fixed Maturity Securities [Member] | Other Debt Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	65	7
Estimated Fair Value, 12 Months or Less	185.3	5.4
Gross Unrealized Losses, Less than 12 Months	(2.5)	(0.2)
Number of Securities, 12 Months or Greater	17	21
Estimated Fair Value, 12 Months or Greater	16.2	28.9
Gross Unrealized Losses, 12 Months or Greater	(0.8)	(3.1)
Equity Securities [Member]
Investment [Line Items]
Number of Securities, 12 Months or Less	426	961
Estimated Fair Value, 12 Months or Less	120.8	149.6
Gross Unrealized Losses, Less than 12 Months	(8.0)	(12.5)
Number of Securities, 12 Months or Greater	0	0
Estimated Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	$ 0	$ 0