Other Comprehensive Income And Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Comprehensive Income (Loss) Before Income Taxes:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	$ (324.9)	$ 157.9	$ 232.1
Reclassification Adjustment for Amounts Included in Net Income	(37.9)	(61.2)	(30.9)
Unrealized Holding Gains (Losses)	(362.8)	96.7	201.2
Foreign Currency Translation Adjustments Arising During the Period Before Reclassification Adjustment	0.2	1.6	0.4
Reclassification Adjustment for Amounts Included in Net Income	0	0	0
Foreign Currency Translation Adjustments	0.2	1.6	0.4
Unrecognized Postretirement Benefit Costs Arising During the Year	61.6	(29.4)	(53.9)
Amortization of Unrecognized Postretirement Benefit Costs	25.0	16.2	8.7
Net Unrecognized Postretirement Benefit Costs	86.6	(13.2)	(45.2)
Other Comprehensive Income (Loss) Before Income Taxes	(276.0)	85.1	156.4
Income Tax Benefit (Expense):
Unrealized Holding Gains and Losses Arising During the Period Before Reclassification Adjustment	115.9	(55.9)	(82.5)
Reclassification Adjustment for Amounts Included in Net Income	13.2	21.5	10.9
Unrealized Holding Gains and Losses	129.1	(34.4)	(71.6)
Foreign Currency Translation Adjustments Arising During the Period Before Reclassification Adjustment	(0.1)	(0.6)	(0.1)
Reclassification Adjustment for Amounts Included in Net Income	0	0	0
Foreign Currency Translation Adjustment	(0.1)	(0.6)	(0.1)
Unrecognized Postretirement Benefit Costs Arising During the Year	(21.6)	10.3	19.0
Amortization of Unrecognized Postretirement Benefit Costs	(8.8)	(5.7)	(3.1)
Net Unrecognized Postretirement Benefit Costs	(30.4)	4.6	15.9
Other Comprehensive Income Tax Benefit (Expense)	$ 98.6	$ (30.4)	$ (55.8)