Discontinued Operations (Schedule Of The Amounts In Net Loss From Discontinued Operations) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
	Jan. 26, 2018	Jan. 31, 2018	Mar. 31, 2018	Mar. 31, 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			$ 32		43
Net income (loss) from discontinued operations			1,110	$ (43)
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			32		27
Accrued and other current liabilities					16
Discontinued operations included in current liabilities			32		$ 43
Revenues			6	135
Production costs and taxes			(50)	(163)
Depreciation, depletion, and amortization			(4)	(15)
Interest income			1
Gain on sale of assets			1,157
Net income (loss) from discontinued operations			$ 1,110	$ (43)