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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Minimum credit limit | 30 days |  |  |  |  |  |
Extended credit terms for trade receivables | 60 days |  |  |  |  |  |
Accounts receivable | $ 9,435,000 | $ 15,392,000 | $ 12,693,000 |  | $ 8,327,000 | $ 16,709,000 | $ 13,819,000
Impairment charges | 5,331,000 | 1,814,000 |  |  |  |  |
Shipping and handling costs | 300,000 | 400,000 | $ 600,000 |  |  |  |
Unrecorded excess tax benefits in additional paid-in-capital account | 0 |  |  |  |  |  |
Scenario, Forecast |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Cumulative-effect adjustment to retained earnings |  |  |  | $ 100,000 |  |  |
Customer one |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Financing receivable | $ 8,100,000 |  |  |  |  |  |
Accounts receivable |  | $ 9,100,000 |  |  |  |  |
Customer Concentration Risk | Customer one | Sales Revenue, Net |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Percentage of company revenue | 17.80% | 18.50% |  |  |  |  |
Customer Concentration Risk | No customers | Sales Revenue, Net |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Percentage of company revenue |  |  | 10.00% |  |  |  |

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