Pension and Postretirement Plans (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Capitalized portion of defined benefit contribution percent	10.00%	12.00%		10.00%	10.00%
Increase (Decrease) in Pension Plan Obligations			$ 1.7
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Curtailment loss			$ 0.3
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year						$ 2.0
Pension and Other Postretirement Benefit Contributions				$ 1.9
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 0.0	$ 0.0		0.0	$ 0.3
Interest cost on projected benefit obligation	4.9	4.8		14.5	14.3
Expected return on plan assets	(6.9)	(7.3)		(20.5)	(21.8)
Curtailment loss				0.0	0.3
Amortization of:
Prior service cost (benefit)	0.1	0.0		0.1	0.1
Actuarial loss	4.7	5.2		14.3	19.7
Total amortization	4.8	5.2		14.4	19.8
Pension / postretirement costs (benefit)	2.8	2.7		8.4	12.9
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year						$ 10.0
Pension and Other Postretirement Benefit Contributions				5.7
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	0.8		2.5	2.5
Expected return on plan assets	0.0	0.0		0.0	0.0
Curtailment loss				0.0	0.0
Amortization of:
Prior service cost (benefit)	(3.7)	(3.9)		(11.1)	(11.6)
Actuarial loss	1.2	1.4		3.7	4.1
Total amortization	(2.5)	(2.5)		(7.4)	(7.5)
Pension / postretirement costs (benefit)	$ (1.6)	$ (1.6)		$ (4.7)	$ (4.8)