Contingencies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Accrued environmental	$ 3,587	$ 3,871
Accrual for Environmental Loss Contingencies, Significant Assumptions	The Company accrues for certain environmental remediation-related activities for which commitments or remediation plans have been developed and for which costs can be reasonably estimated. These estimates are determined based upon currently available facts and circumstances regarding each facility. Actual costs incurred may vary from these estimates due to the inherent uncertainties involved. Future expenditures relating to these environmental remediation efforts are expected to be made over the next 14 years as ongoing costs of remediation programs.
Enogex Federal Court Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	75,000
Enogex State Court Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 105,000