Discontinued Operations (Schedule Of The Amounts In Net Loss From Discontinued Operations) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 26, 2018	Jan. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations included in current assets							$ 121
Discontinued operations included in non-current assets							1,497
Discontinued operations included in current liabilities			$ 22		$ 22		43
Net income (loss) from discontinued operations			10	$ 52	1,120	$ 9
Sale of methane facility assets	$ 2,650	$ 2,650
Disposal Group, Not Discontinued Operations [Member] | Methane Facilities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable							91
Other current assets							30
Discontinued operations included in current assets							121
Property, plant, and equipment							1,681
Accumulated depreciation, depletion, and amortization							(184)
Discontinued operations included in non-current assets							1,497
Accounts payable - trade							27
Accrued and other current liabilities			22		22		16
Discontinued operations included in current liabilities			22		22		$ 43
Revenues				180	6	315
Production costs and taxes			10	(112)	(40)	(275)
Depreciation, depletion, and amortization				(16)	(4)	(31)
Interest income					1
Gain on sale of assets					1,157
Net income (loss) from discontinued operations			$ 10	$ 52	$ 1,120	$ 9