Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities:
Net income	$ 13,677	$ 3,352
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,878	9,408
Stock-based compensation	2,391	2,220
Bad debt expense	187	126
Deferred income taxes	1,640	(1,023)
Changes in operating assets and liabilities:
Accounts receivable, net	14,268	(16,350)
Contract assets and liabilities, net	30,150	42,954
Inventories	(2,534)	(8,202)
Income taxes	(628)	6,439
Prepaid expenses and other current assets	1,071	(1,330)
Accounts payable	(11,264)	(2,174)
Accrued liabilities	(2,305)	(3,051)
Other, net	(1,131)	1,566
Net cash provided by operating activities	53,400	33,935
Investing Activities:
Purchases of short-term investments	(7,330)	(5,869)
Maturities of short-term investments	6,146	13,088
Purchases of property, plant and equipment, net	(4,274)	(3,210)
Net cash provided by (used in) investing activities	(5,458)	4,009
Financing Activities:
Payments on industrial development revenue bonds	(400)	(400)
Shares withheld in lieu of employee tax withholding	(617)	(1,151)
Dividends paid	(9,047)	(8,991)
Net cash used in financing activities	(10,064)	(10,542)
Net increase in cash, cash equivalents and restricted cash	37,878	27,402
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(491)	(542)
Cash, cash equivalents and restricted cash at beginning of period	118,639	61,725
Cash, cash equivalents and restricted cash at end of period	$ 156,026	$ 88,585