CONDENSED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating Activities:
Net income (loss)	$ 348,000	$ (1,725,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	570,000	665,000
Changes in allowance for doubtful accounts	(36,000)	26,000
Deferred income tax expense	0	(205,000)
Stock-based compensation expense	149,000	274,000
Changes in operating assets and liabilities:
Accounts receivable	2,296,000	14,000
Inventories	(63,000)	(20,000)
Income tax receivable	107,000	351,000
Prepaid expenses and other	109,000	82,000
Accounts payable	(131,000)	(276,000)
Accrued liabilities	17,000	(72,000)
Income tax payable	0	14,000
Accrued income taxes	15,000	0
Deferred revenue	659,000	634,000
Net cash provided by (used in) operating activities	4,040,000	(238,000)
Investing Activities:
Purchases of property and equipment	(528,000)	(644,000)
Net cash used in investing activities	(528,000)	(644,000)
Financing Activities:
Cash dividends paid ($0.70 per share)	(14,000)	(8,177,000)
Proceeds from issuance of common stock	49,000	(8,000)
Repurchase of common stock upon vesting of restricted stock awards	(14,000)	0
Repurchase of common stock, net	(187,000)	0
Net cash used in financing activities	(166,000)	(8,185,000)
Increase (decrease) in cash and cash equivalents	3,346,000	(9,067,000)
Cash and cash equivalents at beginning of period	4,695,000	12,267,000
Cash and cash equivalents at end of period	8,041,000	3,200,000
Supplemental disclosures for cash flow information:
Cash paid during the period for income taxes	0	2,000
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable	$ 111,000	$ 65,000