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Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Sep. 30, 2020 USD ($) customer shares | Sep. 30, 2019 USD ($) customer group event shares | Oct. 01, 2019 USD ($)
Accounting Policies [Line Items] |  |  |
Allowance for doubtful accounts | $ 249 | $ 592 |
Accounts receivable, written off | 263 | 33 |
Bad debt expense | $ 80 | $ 39 |
Percentage of inventory estimated using LIFO method | 47.00% | 27.00% |
Reserve for obsolete and excess inventory | $ 3,676 | $ 3,335 |
Depreciation expense | $ 5,883 | $ 5,877 |
Number of asset impairment triggering events | event |  | 3 |
Number of long-lived asset groups under impairment review | group |  | 2 |
Anti-dilutive weighted-average common shares excluded from calculation of diluted earnings per share (in shares) | shares | 207,000 | 196,000 |
Operating lease right-of-use assets, net | $ 17,021 | $ 0 |
Operating lease liability | $ 17,179 |  |
Topic 842 |  |  |
Accounting Policies [Line Items] |  |  |
Operating lease right-of-use assets, net |  |  | $ 18,059
Operating lease liability |  |  | $ 18,059
Restricted shares |  |  |
Accounting Policies [Line Items] |  |  |
Anti-dilutive weighted-average common shares excluded from calculation of diluted earnings per share (in shares) | shares | 0 | 0 |
Minimum |  |  |
Accounting Policies [Line Items] |  |  |
Finite-lived intangible asset, useful life (in years) | 1 year |  |
Maximum |  |  |
Accounting Policies [Line Items] |  |  |
Finite-lived intangible asset, useful life (in years) | 10 years |  |
Building and Building Improvements | Minimum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 5 years |  |
Building and Building Improvements | Maximum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 40 years |  |
Machinery and Equipment | Minimum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 3 years |  |
Machinery and Equipment | Maximum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 20 years |  |
Computer Software | Minimum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 3 years |  |
Computer Software | Maximum |  |  |
Accounting Policies [Line Items] |  |  |
Property, plant and equipment, useful life (in years) | 7 years |  |
Customer Concentration Risk | Sales Revenue, Net |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 47.00% | 44.00% |
Number of major customers | customer | 3 | 3 |
Customer Concentration Risk | Sales Revenue, Net | Total Customers and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 49.00% | 50.00% |
Number of major customers | customer | 4 | 4 |
Customer Concentration Risk | Sales Revenue, Net | Major Customer One and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 16.00% | 14.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Two and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 13.00% | 13.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Three and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 10.00% | 12.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Four and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 10.00% | 11.00% |
Customer Concentration Risk | Accounts Receivable |  |  |
Accounting Policies [Line Items] |  |  |
Number of major customers | customer | 2 | 2 |
Customer Concentration Risk | Accounts Receivable | Total Customers and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Number of major customers | customer | 3 | 3 |
Customer Concentration Risk | Accounts Receivable | Major Customer One and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 13.00% | 15.00% |
Customer Concentration Risk | Accounts Receivable | Major Customer Two and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 13.00% | 14.00% |
Customer Concentration Risk | Accounts Receivable | Major Customer Three and Their Subcontractors |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 12.00% | 12.00% |
Customer Concentration Risk | Accounts Receivable | Customer One |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 30.00% | 10.00% |
Customer Concentration Risk | Accounts Receivable | Customer Two |  |  |
Accounting Policies [Line Items] |  |  |
Percentage of concentration risk | 30.00% | 10.00% |

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