Commitments and Contingencies, Environmental (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Environmental Contingency
Environmental accrual	$ 18.8
Expected period related to remediation expenditures for environmental contingencies period	30 years
Potential increase in environmental costs	$ 24.7
Minimum
Environmental Contingency
Period for final feasibility study	18 months
Maximum
Environmental Contingency
Period for final feasibility study	24 months