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Nature of Operations and Summary of Significant Accounting Policies - Schedule of Changes in Allowance for Slow Move and Obsolete Inventories (Detail) - USD ($) | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Inventory Disclosure [Abstract] |  |  |
Balance, beginning of year | $ 3,869,000 | $ 3,310,000 | $ 3,139,000
Charged to cost of sales | 77,000 | 621,000 | 144,000
Disposal of inventory, net of recoveries | (120,000) | (62,000) | 27,000
Balance, end of year | $ 3,826,000 | $ 3,869,000 | $ 3,310,000

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- Definition Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6(c)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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