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	6 Months Ended	12 Months Ended
	Jun. 30, 2014 securities	Dec. 31, 2013 securities
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	1,138	3,451
Estimated Fair Value, Less Than 12 Months	$ 1,356.8	$ 6,636.9
Gross Unrealized Loss, Less Than 12 Months	(13.3)	(244.5)
Number of Securities, 12 Months or Greater	941	250
Estimated Fair Value, 12 Months or Greater	2,008.4	301.7
Gross Unrealized Losses, 12 Months or Greater	(51.7)	(33.3)
Equity Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	277	426
Estimated Fair Value, Less Than 12 Months	68.4	120.8
Gross Unrealized Loss, Less Than 12 Months	(4.5)	(8.0)
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 Maturities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	861	3,025
Estimated Fair Value, Less Than 12 Months	1,288.4	6,516.1
Gross Unrealized Loss, Less Than 12 Months	(8.8)	(236.5)
Number of Securities, 12 Months or Greater	941	250
Estimated Fair Value, 12 Months or Greater	2,008.4	301.7
Gross Unrealized Losses, 12 Months or Greater	(51.7)	(33.3)
Fixed Maturities [Member] | United States Government Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	4	27
Estimated Fair Value, Less Than 12 Months	41.7	179.2
Gross Unrealized Loss, Less Than 12 Months	0	(3.4)
Number of Securities, 12 Months or Greater	4	0
Estimated Fair Value, 12 Months or Greater	10.1	0
Gross Unrealized Losses, 12 Months or Greater	(0.3)	0
Fixed Maturities [Member] | Government Sponsored Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	5	22
Estimated Fair Value, Less Than 12 Months	8.4	73.4
Gross Unrealized Loss, Less Than 12 Months	0	(1.3)
Number of Securities, 12 Months or Greater	16	0
Estimated Fair Value, 12 Months or Greater	32.6	0
Gross Unrealized Losses, 12 Months or Greater	(0.7)	0
Fixed Maturities [Member] | States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	107	806
Estimated Fair Value, Less Than 12 Months	287.2	2,070.9
Gross Unrealized Loss, Less Than 12 Months	(1.1)	(90.1)
Number of Securities, 12 Months or Greater	237	42
Estimated Fair Value, 12 Months or Greater	645.0	82.4
Gross Unrealized Losses, 12 Months or Greater	(13.0)	(9.6)
Fixed Maturities [Member] | Corporate Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	669	1,448
Estimated Fair Value, Less Than 12 Months	754.8	2,586.6
Gross Unrealized Loss, Less Than 12 Months	(6.2)	(95.2)
Number of Securities, 12 Months or Greater	366	107
Estimated Fair Value, 12 Months or Greater	677.7	81.3
Gross Unrealized Losses, 12 Months or Greater	(20.4)	(15.5)
Fixed Maturities [Member] | Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	37	605
Estimated Fair Value, Less Than 12 Months	92.5	1,243.0
Gross Unrealized Loss, Less Than 12 Months	(1.2)	(41.4)
Number of Securities, 12 Months or Greater	270	80
Estimated Fair Value, 12 Months or Greater	517.9	116.2
Gross Unrealized Losses, 12 Months or Greater	(15.2)	(7.1)
Fixed Maturities [Member] | Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	12	52
Estimated Fair Value, Less Than 12 Months	30.6	177.7
Gross Unrealized Loss, Less Than 12 Months	(0.1)	(2.6)
Number of Securities, 12 Months or Greater	17	4
Estimated Fair Value, 12 Months or Greater	56.0	5.6
Gross Unrealized Losses, 12 Months or Greater	(0.6)	(0.3)
Fixed Maturities [Member] | Other Debt Securities [Member]
Schedule of Investments [Line Items]
Number of Securities, Less Than 12 Months	27	65
Estimated Fair Value, Less Than 12 Months	73.2	185.3
Gross Unrealized Loss, Less Than 12 Months	(0.2)	(2.5)
Number of Securities, 12 Months or Greater	31	17
Estimated Fair Value, 12 Months or Greater	69.1	16.2
Gross Unrealized Losses, 12 Months or Greater	$ (1.5)	$ (0.8)