Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss) Attributable to Parent	$ 4.0	$ 29.7	$ 1.9	$ 43.2
Other Comprehensive Income (Loss) Before Income Taxes:
Unrealized Holding Gains (Losses)	124.8	(184.0)	225.5	(130.7)
Foreign Currency Translation Adjustments	(0.1)	0.1	0.0	(0.8)
Decrease (Increase) in Net Unrecognized Postretirement Benefit Costs	(16.0)	6.1	(14.2)	11.5
Other Comprehensive Income (Loss) Before Income Taxes	108.7	(177.8)	211.3	(120.0)
Other Comprehensive Income Tax Benefit (Expense)	(38.3)	62.8	(74.5)	42.6
Other Comprehensive Income (Loss)	70.4	(115.0)	136.8	(77.4)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 74.4	$ (85.3)	$ 138.7	$ (34.2)