Pension and Postretirement Plans (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Capitalized portion of defined benefit contribution percent	12.00%		10.00%	12.00%	10.00%
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year						$ 20.0
Amortization of:
Gain (Loss) on Curtailments	$ 0.0	$ 0.3	$ 0.0	$ 0.3	$ 0.0
Increase (Decrease) in Pension Plan Obligations		$ 1.7
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Contributions				11.9
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	0.0		0.3	0.3	0.8
Interest cost on projected benefit obligation	4.8		5.2	14.3	15.7
Expected return on plan assets	(7.3)		(7.0)	(21.8)	(21.1)
Amortization of:
Prior service cost (benefit)	0.0		0.1	0.1	0.2
Actuarial loss	5.2		4.3	19.7	13.0
Total amortization	5.2		4.4	19.8	13.2
Benefit costs	2.7		2.9	12.9	8.6
Gain (Loss) on Curtailments				0.3	0.0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Contributions				6.1
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	0.1		0.1	0.2	0.2
Interest cost on projected benefit obligation	0.8		1.0	2.5	3.0
Expected return on plan assets	0.0		0.0	0.0	0.0
Amortization of:
Prior service cost (benefit)	(3.9)		(3.9)	(11.6)	(11.6)
Actuarial loss	1.4		1.4	4.1	4.1
Total amortization	(2.5)		(2.5)	(7.5)	(7.5)
Benefit costs	$ (1.6)		$ (1.4)	(4.8)	(4.3)
Gain (Loss) on Curtailments				$ 0.0	$ 0.0