CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 62,000	$ 243,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	285,000	282,000
Loss (income) from investment in unconsolidated entities	30,000	(112,000)
Distributed earnings from unconsolidated entities	0	315,000
Accretion of asset retirement obligations	7,000	6,000
Accrued interest from short term loan receivable	(2,000)	0
Deferred income taxes	(244,000)	(50,000)
Changes in:
Accounts receivable	(36,000)	376,000
Other current assets	(184,000)	9,000
Accounts payable and accrued expenses	(100,000)	94,000
Deferred revenue	511,000	424,000
Income taxes payable	330,000	200,000
Net cash provided by operating activities	659,000	1,787,000
Cash flows from investing activities:
Advances to unconsolidated entities	(820,000)	(37,000)
Increase in due from related parties	0	(21,000)
Net cash used in investing activities	(820,000)	(58,000)
Cash flows from financing activities:
Repayment of capital lease obligations	(257,000)	(250,000)
Net cash used in financing activities	(257,000)	(250,000)
Net change in cash and cash equivalents	(418,000)	1,479,000
Cash and cash equivalents - beginning of year	2,684,000	1,962,000
Cash and cash equivalents - end of year	2,266,000	3,441,000
Cash paid for:
Interest	$ 35,000	$ 40,000