CONDENSED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities:
Net income (loss)	$ 993,000	$ (1,274,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	860,000	1,001,000
Changes in allowance for doubtful accounts	(16,000)	16,000
Deferred income tax expense	(9,000)	(205,000)
Stock-based compensation expense	277,000	317,000
Changes in operating assets and liabilities:
Accounts receivable	586,000	(2,040,000)
Inventories	(22,000)	(1,000)
Income tax receivable	266,000	355,000
Prepaid expenses and other	80,000	192,000
Accounts payable	408,000	777,000
Accrued liabilities	253,000	377,000
Income tax payable	0	20,000
Accrued income taxes	23,000	0
Deferred revenue	381,000	586,000
Net cash provided by operating activities	4,080,000	121,000
Investing Activities:
Purchases of property and equipment	(877,000)	(822,000)
Net cash used in investing activities	(877,000)	(822,000)
Financing Activities:
Cash dividends paid ($0.70 per share)	(14,000)	(8,177,000)
Proceeds from issuance of common stock	49,000	(14,000)
Repurchase of common stock upon vesting of restricted stock awards	(74,000)	0
Repurchase of common stock, net	(269,000)	0
Net cash used in financing activities	(308,000)	(8,191,000)
Increase (decrease) in cash and cash equivalents	2,895,000	(8,892,000)
Cash and cash equivalents at beginning of period	4,695,000	12,267,000
Cash and cash equivalents at end of period	7,590,000	3,375,000
Supplemental disclosures for cash flow information:
Cash paid during the period for income taxes	84,000	2,000
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable	$ 96,000	$ 115,000