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Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 USD ($) | Sep. 30, 2019 USD ($) customer group event segment shares | Sep. 30, 2018 USD ($) customer segment shares | Oct. 01, 2019 USD ($)
Accounting Policies [Line Items] |  |  |  |
Number of operating segments | segment |  | 1 | 1 |
Allowance for doubtful accounts |  | $ 592 | $ 520 |
Accounts receivable, written off |  | 33 | 186 |
Bad debt expense |  | $ 39 | $ 415 |
Percentage of inventory estimated using LIFO method |  | 27.00% | 54.00% |
Reserve for obsolete and excess inventory |  | $ 3,335 | $ 3,979 |
Depreciation expense |  | $ 5,877 | 6,754 |
Number of asset impairment triggering events | event |  | 3 |  |
Number of long-lived asset groups under impairment review | group |  | 2 |  |
Assets held for sale |  | $ 0 | 35 |
Gain on disposal and impairment of assets | $ 282 | 282 | 905 |
Proceeds from sale of building, machinery and equipment | $ 317 |  |  |
Other receivables |  | $ 3,500 | $ 0 |
Restricted shares included in calculation of net loss per share (in shares) | shares |  | 196,000 | 144,000 |
Performance obligation, description of timing |  | one year or less |  |
Research and development expense |  | $ 0 | $ 0 |
Restricted Stock |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Restricted shares included in calculation of net loss per share (in shares) | shares |  | 0 | 0 |
Subsidiaries |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Rental income |  | $ 78 | $ 413 |
Minimum |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Intangible assets amortized over useful lives (in years) |  | 1 year |  |
Minimum | Subsequent event | Accounting Standards Update 2016-02 |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Right-of-use assets |  |  |  | $ 16,106
Operating lease liability |  |  |  | 16,106
Maximum |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Intangible assets amortized over useful lives (in years) |  | 10 years |  |
Maximum | Subsequent event | Accounting Standards Update 2016-02 |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Right-of-use assets |  |  |  | 20,218
Operating lease liability |  |  |  | $ 20,218
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 |  | 44.00% | 31.00% |
Number of major customers | customer |  | 3 | 2 |
Customer Concentration Risk | Sales Revenue, Net | Total Customers And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 50.00% | 38.00% |
Number of major customers | customer |  | 4 | 3 |
Customer Concentration Risk | Sales Revenue, Net | Major Customer One And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 14.00% | 14.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Two And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 13.00% | 12.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Three And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 12.00% | 12.00% |
Customer Concentration Risk | Sales Revenue, Net | Major Customer Four And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 11.00% |  |
Customer Concentration Risk | Accounts Receivable |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Number of major customers | customer |  | 2 | 3 |
Customer Concentration Risk | Accounts Receivable | Total Customers And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Number of major customers | customer |  | 3 | 5 |
Customer Concentration Risk | Accounts Receivable | Major Customer One And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 15.00% | 16.00% |
Customer Concentration Risk | Accounts Receivable | Major Customer Two And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 14.00% | 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 | Major Customer Four And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  |  | 11.00% |
Customer Concentration Risk | Accounts Receivable | Major Customer Five And Their Subcontractors |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  |  | 11.00% |
Customer Concentration Risk | Accounts Receivable | Customer One |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 10.00% | 10.00% |
Customer Concentration Risk | Accounts Receivable | Customer Two |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  | 10.00% | 10.00% |
Customer Concentration Risk | Accounts Receivable | Customer Three |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Percentage of concentration risk |  |  | 10.00% |
Effect of Accounting Changes | Accounting Standards Update 2014-09 |  |  |  |
Accounting Policies [Line Items] |  |  |  |
Reserve for obsolete and excess inventory |  | $ 366 |  |
LIFO reserve |  | $ 508 |  |

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