Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (16.3)	$ 37.9	$ (14.4)	$ 81.1
Other Comprehensive Income (Loss) Before Income Taxes:
Unrealized Holding Gains (Losses)	(8.3)	0.0	217.2	(130.7)
Foreign Currency Translation Adjustments	0.0	(0.3)	0.0	(1.1)
Decrease (Increase) in Net Unrecognized Postretirement Benefit Costs	0.4	5.8	(13.8)	17.3
Other Comprehensive Income (Loss) Before Income Taxes	(7.9)	5.5	203.4	(114.5)
Other Comprehensive Income Tax Benefit (Expense)	2.9	(1.8)	(71.6)	40.8
Other Comprehensive Income (Loss)	(5.0)	3.7	131.8	(73.7)
Total Comprehensive Income (Loss)	$ (21.3)	$ 41.6	$ 117.4	$ 7.4