Organization and Accounting Policies (Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset commodity	$ 3,730	$ 3,520
Assets	3,730	3,520
SARs liability	2,516	1,007
SARs liability	652	625
Liabilities	3,168	1,632
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset commodity	3,730	3,520
Assets	3,730	3,520
SARs liability	2,516	1,007
SARs liability	652	625
Liabilities	$ 3,168	$ 1,632