Commitments and Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Commitments and Contingencies [Line Items]
Purchase Commitments Physical Commodity Requirements Utilization Period	3 years
Construction in Progress Expenditures Incurred but Not yet Paid	$ 155.1
Maximum | Physical Commodity and Commodity Transportation [Member]
Commitments and Contingencies [Line Items]
Long-term Purchase Commitment, Period	6 years
Maximum | Air Products [Member]
Commitments and Contingencies [Line Items]
Long-term Purchase Commitment, Period	14 years