Changes in Equity and Comprehensive Income Changes in Equity and Comprehensive Income (Details of Accumulated Other Comprehensive Income Components) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ 107.5				$ 109.8
Income Tax Expense (Benefit)	(31.3)	$ (27.1)	$ (77.9)	$ (77.7)
Amounts reclassified from accumulated other comprehensive income			5.2
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	2.5	2.9	7.5
Income Tax Expense (Benefit)	0.9	0.9	2.3
Amounts reclassified from accumulated other comprehensive income	(1.6)	(2.0)	5.2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Prior-Service Costs, Pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
PriorServiceCostsCOS	(0.3)	(0.1)	(0.8)	(0.3)
PriorServiceCostSG&A	0.1	0.0	0.2	0.0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(0.2)	(0.1)	(0.6)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Loss (Gain), Pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined Benefit Plan, Amortization of Gains (Losses)	2.9	3.1	8.7
NetlossgainCOS	3.9	4.2	11.8	12.6
NetlossgainSG&A	(1.0)	(1.1)	(3.1)	$ (3.3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Prior-Service Costs, Postretirement [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(0.1)	(0.1)	(0.3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Loss(Gain), Postretirement [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined Benefit Plan, Amortization of Gains (Losses)	$ (0.1)	$ 0.0	$ (0.3)