CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 127,000	$ 139,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property and equipment	0	570,000
Amortization of operating lease right-of-use asset	17,000	0
Loss from investments in unconsolidated entities, net	746,000	190,000
Accrued interest from notes receivable	(82,000)	(4,000)
Accretion of asset retirement obligations	0	13,000
Deferred income taxes	(183,000)	(390,000)
Changes in:
Accounts receivable	(93,000)	243,000
Income taxes receivable	90,000	325,000
Other current assets	36,000	(120,000)
Accounts payable and accrued expenses	(11,000)	(139,000)
Deferred revenue	312,000	497,000
Operating lease right-of-use liability	(17,000)	0
Net cash provided by operating activities	942,000	1,324,000
Cash flows from investing activities:
Advances made under loans to unconsolidated entities	(928,000)	(1,276,000)
Repayments from loans to unconsolidated entities	351,000	0
Principal payments received under sales-type sublease	407,000	0
Net cash used in investing activities	(170,000)	(1,276,000)
Cash flows from financing activities:
Repayment of finance lease obligations	(673,000)	(453,000)
Net cash used in financing activities	(673,000)	(453,000)
Net change in cash and cash equivalents	99,000	(405,000)
Cash and cash equivalents - beginning of year	1,519,000	2,684,000
Cash and cash equivalents - end of year	1,618,000	2,279,000
Cash paid for:
Interest	58,000	60,000
Income taxes	140,000	244,000
Supplemental disclosure of noncash investing and financing activities:
Recognition of a right-of-use asset	161,000	0
Recognition of a right-of-use liability	176,000	0
Derecognition of deferred rent liability (previously included in accounts payable and accrued expenses)	$ 15,000	$ 0