Pension and Postretirement Plans Pension and Postretirement Assumptions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Healthcare cost trend	6.50%		6.50%
Rate to which the cost trend is assumed to decline (ultimate trend rate)	4.50%		4.50%
Year the rates reach the ultimate trend rate	2018		2017
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Service and interest costs for 2014	0.2
Service and interest costs for 2014	(0.1)
Postretirement benefit obligation at December 31, 2014	5.0
Postretirement benefit obligation at December 31, 2014	(4.5)
Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	4.20%	[1]	3.30%		3.90%
Expected long-term rate of return	7.75%		7.75%		7.75%
Future compensation growth rate	0.00%		3.00%		3.00%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	4.10%	[2]	3.40%		3.60%
Expected long-term rate of return	0.00%		0.00%		0.00%
Future compensation growth rate	0.00%		0.00%		0.00%
Discount rate before remeasurement of pension or postretirement liability [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate			3.10%	[2]
Discount rate after remeasurement of pension or postretirement liability [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate			3.90%	[2]

[1] Discount rate used for the remeasurement of the management pension plan in May 2013 was consistent with the discount rate previously established.

[2] For the period January 1, 2013 through July 31, 2013, the date of the remeasurement, we used a 3.10% discount rate. From that date through December 31, 2013, we used a 3.90% discount rate.