Commitments And Contingencies (Narrative) (Details)	9 Months Ended
	Sep. 30, 2017 USD ($) $ / bbl	Sep. 30, 2015 USD ($)
Loss Contingencies [Line Items]
Decrease in compensation	$ 366,000
Period of trailing average of WTI	30 days
Incidence Of Non-Compliance [Member]
Loss Contingencies [Line Items]
Maximum potential loss		$ 386,000
Litigation [Member]
Loss Contingencies [Line Items]
Requested recovery amount	$ 188,000
Minimum [Member]
Loss Contingencies [Line Items]
Compensation reduction until WTI posting | $ / bbl	70
Compensation reimbursement at WTI posting | $ / bbl	85