Postretirement Benefits Other Than Pensions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) employees	Dec. 31, 2014 USD ($)
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of retired employees covered | employees	500
Number of active employees covered | employees	250
Effect of one percentage point increase on accumulated postretirement benefit obligation	$ 1.5	$ 1.7
Effect of one percentage point increase on service and interest cost components	0.1	$ 0.1
Amounts that will be amortized from AOCI in next Fiscal Year	1.3
Estimated future employer contributions in next fiscal year	$ 3.3
Medical Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	7.00%	8.00%
Health care cost trend rate assumed for future years	5.00%	5.00%
Prescription Drug Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	11.00%	7.50%
Health care cost trend rate assumed for future years	5.00%	5.00%