Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Reconciliation of net income to net cash provided by operating activities
Net income	$ 2,684,000	$ 2,835,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	926,000	821,000
Gain on sale of fixed assets	(51,000)	(32,000)
Stock compensation	411,000	0
Deferred taxes	526,000	574,000
(Increase) decrease in
Accounts receivable - billed	(1,640,000)	(364,000)
Accounts receivable - unbilled	20,000	(73,000)
Allowance for doubtful accounts	(139,000)	(29,000)
Inventories	(937,000)	(85,000)
Refundable income taxes	(1,107,000)	133,000
Prepaid expenses and other assets	(285,000)	(116,000)
Increase (decrease) in
Accounts payable - trade	969,000	396,000
Accrued expenses and other liabilities	294,000	46,000
Deferred revenue	420,000	(52,000)
Accrued compensation	347,000	433,000
Customer deposits	488,000	(492,000)
Net cash provided by operating activities	2,926,000	3,995,000
Cash Flows From Investing Activities
Purchases of investment securities available-for-sale	(32,000)	(24,000)
Purchases of property and equipment	(2,741,000)	(3,745,000)
Proceeds from sale of fixed assets	46,000	58,000
Net cash absorbed by investing activities	(2,727,000)	(3,711,000)
Cash Flows From Financing Activities
Proceeds from the line-of-credit	0	1,450,000
Repayments on the line-of-credit	0	(1,802,000)
Proceeds from long-term borrowings	184,000	2,233,000
Repayments of long-term borrowings	(584,000)	(461,000)
Dividends paid on common stock	(49,000)	0
Proceeds from options exercised	117,000	83,000
Net cash provided by or (absorbed by) financing activities	(332,000)	1,503,000
Net increase (decrease) in cash and cash equivalents	(133,000)	1,787,000
Cash and cash equivalents
Cash and cash equivalents, beginning of year	3,523,000
Cash and cash equivalents, end of year	$ 3,390,000	3,523,000	$ 1,736,000
Cash payments for interest		184,000	163,000
Cash payments for income taxes		$ 1,292,000	$ 770,000