Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operations:
Net income	$ 10,217,000	$ 8,791,000
Adjustments to reconcile net income to cash flows provided by operating activities:
Purchases of marketable securities	(152,063,000)	(188,082,000)
Proceeds from sale and maturity of marketable securities	152,678,000	186,812,000
Change in fair value of marketable securities	(1,324,000)	1,256,000
Deferred income taxes	(25,000)	(1,082,000)
Depreciation and amortization	1,188,000	1,010,000
Provision for doubtful accounts	100,000	80,000
Stock-based compensation	53,000	53,000
Loss on sale of fixed assets		3,000
Changes in assets and liabilities:
Accounts receivable	(589,000)	(495,000)
Costs and estimated earnings in excess of billings	(8,622,000)	(1,568,000)
Inventories	(1,781,000)	443,000
Prepaid expenses and other current assets	959,000	705,000
Accounts payable	756,000	1,773,000
Customer deposits	(2,101,000)	(4,883,000)
Accrued expenses and other current liabilities	577,000	98,000
Total adjustments	(10,194,000)	(3,877,000)
Cash flows provided by operating activities	23,000	4,914,000
Cash flows used in investing activities:
Capital expenditures	(1,600,000)	(3,317,000)
Cash flows used in investing activities	(1,600,000)	(3,317,000)
Cash flows from financing activities:
Proceeds from stock option exercises		381,000
Cash flows provided by financing activities		381,000
Net increase (decrease) in cash	(1,577,000)	1,978,000
Cash at:
Beginning of period	8,012,000	22,933,000
End of period	$ 6,435,000	$ 24,911,000