Note 6 - Discontinued Operations - Information by Major Classes of Line Items Disclosed as Discontinued Operations in the Consolidated Statements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pretax loss of discontinued operations related to major classes of pretax profit	$ (2,332,000)	$ (1,807,000)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax, Total		129,000
Pretax loss on impairment		(130,000)
Income tax benefit
Total loss on discontinued operations that is presented in the Statements of Operations	(2,332,000)	(1,807,000)
Dillco Fluid Service, Inc [Member]
Accounts receivable, net	175,000	978,000
Inventories
Property and equipment, net	1,373,000	2,376,000
Receivable from equipment sales		760,000
Prepaid expenses and other current assets	12,000	45,000
Other assets	57,000
Total major classes of assets of the discontinued operations	1,617,000	4,159,000
Accounts payable and accrued liabilities	47,000	341,000
Other liabilities	59,000
Total liabilities included as part of discontinued operations	106,000	341,000
Revenue	3,303,000	6,593,000
Cost of sales	(4,446,000)	(6,908,000)
Sales, general, and administrative expenses	(23,000)	(101,000)
Depreciation and amortization	(1,177,000)	(1,393,000)
Other income and expense items that are not major	11,000	3,000
Pretax loss of discontinued operations related to major classes of pretax profit	(2,332,000)	(1,806,000)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax, Total		129,000
Pretax loss on impairment		(130,000)
Income tax benefit
Total loss on discontinued operations that is presented in the Statements of Operations	$ (2,332,000)	$ (1,807,000)