Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension [Member]
Components of Net Periodic Benefit Expense (Income) [Abstract]
Service Cost	$ 2.6	$ 2.0	$ 7.6	$ 6.2
Interest Cost	7.5	7.5	22.4	22.4
Expected Return on Plan Assets	(10.2)	(9.6)	(30.5)	(28.7)
Amortization of Prior Service Costs (Credits)	0.0	0.1	0.1	0.2
Amortization of Net Loss	4.4	3.6	13.4	10.7
Net Periodic Benefit Expense (Income)	4.3	3.6	13.0	10.8
Contributions			0.0	19.5
Estimated Future Contributions			0.0
Other Postretirement [Member]
Components of Net Periodic Benefit Expense (Income) [Abstract]
Service Cost	1.0	0.9	3.2	2.6
Interest Cost	1.8	1.8	5.4	5.5
Expected Return on Plan Assets	(2.7)	(2.5)	(8.2)	(7.7)
Amortization of Prior Service Costs (Credits)	(0.7)	(0.7)	(2.2)	(1.9)
Amortization of Net Loss	0.1	0.1	0.3	0.3
Net Periodic Benefit Expense (Income)	$ (0.5)	$ (0.4)	(1.5)	(1.2)
Contributions			0.0	$ 0.0
Estimated Future Contributions			$ 0.0