Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 8,235	$ 8,266	$ 63,100
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	3,757	2,506	2,952
Stock-based compensation expense	3,602	2,086	4,586
Deferred income taxes	0	0	24,080
Provision adjustments related to doubtful accounts	23	23	556
Provision adjustments related to product warranty	573	376	838
Change in fair value of financial instruments	0	0	(122)
Gain from change in estimate on ARO obligation	(45)	0	(845)
Reclassification of foreign currency translation adjustment	0	0	(744)
Impairments of equipment	506	0	0
Recognition of previously deferred gain on sale of assets from discontinued operations	0	(3,804)	0
Net (gain) loss on disposal of equipment	(456)	(41)	237
Settlement of customer related warranty claim	0	0	(442)
Other	(5)	(1,422)	(552)
Total non-cash adjustments	7,955	(276)	(58,408)
Changes in operating assets and liabilities:
Accounts receivable	(3,859)	(1,171)	3,526
Inventory	(140)	(10,904)	(3,440)
Other assets	(4,455)	148	359
Accounts payable	2,095	3,179	(3,231)
Accrued expenses and other current liabilities	1,870	(4,794)	(5,823)
Total change in operating assets and liabilities	(4,489)	(13,542)	(8,609)
Net cash provided by (used in) operating activities	11,701	(5,552)	(3,917)
Cash flows from investing activities:
Purchase of equipment	(9,600)	(5,779)	(2,799)
Receipt of escrow funds from sale of assets	0	1,853	0
Proceeds from disposal of property, plant and equipment	474	100	50
Net cash (used in) provided by investing activities	(9,126)	(3,826)	164,169
Cash flows from financing activities:
Payments from borrowings of credit facilities	0	0	(26,518)
Repurchases of common stock	0	0	(45,650)
Payment of special dividend	0	(39,214)	0
Proceeds from stock plans	1,306	960	1,902
Net cash provided by (used in) financing activities	1,306	(38,254)	(70,266)
Effect of exchange rate changes on foreign currency	3	242	105
Net increase (decrease) in cash, cash equivalents and restricted cash	3,884	(47,390)	90,091
Cash, cash equivalents and restricted cash at beginning of period	64,870	112,260	22,169
Cash, cash equivalents and restricted cash at end of period	68,754	64,870	112,260
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	71	88	194
Cash paid during the period for income taxes	114	124	938
NON-CASH INVESTING AND FINANCING ACTIVITIES
Changes in accounts payable related to purchases of equipment	(861)	282	514
Issuance of common stock to Board of Directors	331	263	413
Photovoltaics Business [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of business	0	0	(86,958)
Cash flows from investing activities:
Proceeds from sale of business	0	0	149,936
Digital Products Business [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of business	0	0	(1,994)
Cash flows from investing activities:
Proceeds from sale of business	$ 0	$ 0	$ 16,982