Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 29.7	$ 9.3	$ 43.2	$ 44.4
Other Comprehensive Income (Loss) Before Income Taxes:
Unrealized Holding Gains (Losses)	(184.0)	97.6	(130.7)	217.6
Foreign Currency Translation Adjustments	0.1	(0.2)	(0.8)	(0.2)
Amortization of Net Unrecognized Postretirement Benefit Costs	6.1	1.9	11.5	3.9
Other Comprehensive Income (Loss) Before Income Taxes	(177.8)	99.3	(120.0)	221.3
Other Comprehensive Income Tax Benefit (Expense)	62.8	(34.9)	42.6	(78.0)
Other Comprehensive Income (Loss)	(115.0)	64.4	(77.4)	143.3
Total Comprehensive Income (Loss)	$ (85.3)	$ 73.7	$ (34.2)	$ 187.7