Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Sep. 30, 2017
Current assets:
Cash and cash equivalents	$ 65,312	$ 68,333
Restricted cash	193	421
Accounts receivable, net of allowance of $598 and $22, respectively	14,870	22,265
Inventory	24,152	25,139
Prepaid expenses and other current assets	11,553	8,527
Total current assets	116,080	124,685
Property, plant, and equipment, net	17,577	16,635
Non-current inventory	2,092	2,686
Other non-current assets	245	78
Total assets	135,994	144,084
Current liabilities:
Accounts payable	11,519	11,818
Accrued expenses and other current liabilities	11,332	9,825
Total current liabilities	22,851	21,643
Asset retirement obligations	1,648	1,638
Other long-term liabilities	68	29
Total liabilities	24,567	23,310
Commitments and contingencies (Note 11)
Shareholders’ equity:
Common stock, no par value, 50,000 shares authorized; 34,396 shares issued and 27,486 shares outstanding as of June 30, 2018; 33,938 shares issued and 27,028 shares outstanding as of September 30, 2017	732,806	730,906
Treasury stock at cost; 6,910 shares	(47,721)	(47,721)
Accumulated other comprehensive income	881	561
Accumulated deficit	(574,539)	(562,972)
Total shareholders’ equity	111,427	120,774
Total liabilities and shareholders’ equity	$ 135,994	$ 144,084