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Nature of Operations and Summary of Significant Accounting Policies - Schedule of Changes in Allowance for Doubtful Accounts (Detail) - USD ($) | 12 Months Ended
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Sep. 30, 2019 | Sep. 30, 2018
Receivables [Abstract] |  |  |
Balance, beginning of year | $ 313,000 | $ 207,000 |
Provision for doubtful accounts | 175,000 | 210,000 | [1]
Provision for estimated returns and allowances | 315,000 | 265,000 |
Uncollectible accounts writtenoff | (71,000) | (76,000) |
Returns and allowances issued | (273,000) | (293,000) |
Balance, end of year | $ 459,000 | $ 313,000 |
[1] | The amounts for the year ended September 30, 2018 have been adjusted to reflect the change in inventory accounting method, as described in Notes 1 and 2 to the Consolidated Financial Statements.

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- Definition Amount of allowance for credit loss on accounts receivable, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446 + Details
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- Definition Amount of direct write-downs of accounts receivable charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 + Details
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