Summary of Significant Accounting Policies - Narrative (Details)			12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 15, 2017 USD ($)	Sep. 30, 2018 USD ($) customer segment shares	Sep. 30, 2017 USD ($) customer segment shares
Accounting Policies [Line Items]
Number of operating segments | segment			1	1
Allowance for doubtful accounts			$ 520,000	$ 330,000
Accounts receivable, written off			186,000	461,000
Bad debt expense			$ 415,000	$ 77,000
Percentage of inventory estimated using LIFO method			54.00%	38.00%
Reserve for obsolete and excess inventory			$ 3,979,000	$ 3,859,000
Depreciation expense			6,754,000	7,820,000
Impairment of assets to be disposed of				4,786,000
Impairment of intangible assets			0	2,289,000
ERP impairment charges				174,000
Assets held for sale			35,000	$ 2,524,000
(Gain) loss on disposal of operating assets or impairment of operating assets			500,000
Proceeds from sale of machinery and equipment			$ 515,000
Restricted shares included in calculation of net loss per share (in shares) | shares			144,000	93,000
Performance obligation, description of timing			one year or less
Research and development expense			$ 0	$ 0
Interest Rate Swap
Accounting Policies [Line Items]
Derivative, gain on derivative	$ 43,000
Derivative, notional amount				4,059,000
Derivative asset				$ 4,000
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, quarterly installment			$ 103,000
Rental income			$ 78,000	$ 413,000
Minimum
Accounting Policies [Line Items]
Intangible assets amortized over useful lives (in years)			1 year
Minimum | Forecast | Accounting Standards Update 2014-09 | Retained Earnings
Accounting Policies [Line Items]
Cumulative effect of new accounting principal in period of adoption			$ 2,300,000
Maximum
Accounting Policies [Line Items]
Intangible assets amortized over useful lives (in years)			10 years
Maximum | Forecast | Accounting Standards Update 2014-09 | Retained Earnings
Accounting Policies [Line Items]
Cumulative effect of new accounting principal in period of adoption			$ 3,100,000
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
Accounting Policies [Line Items]
Impairment of machinery and equipment				$ 2,497,000
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			31.00%	22.00%
Number of major customers | customer			2	2
Customer Concentration Risk | Sales Revenue, Net | Total Customers And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			38.00%	35.00%
Number of major customers | customer			3	3
Customer Concentration Risk | Sales Revenue, Net | Major Customer One And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			14.00%
Customer Concentration Risk | Sales Revenue, Net | Major Customer Two And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			12.00%	13.00%
Customer Concentration Risk | Sales Revenue, Net | Major Customer Three And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			12.00%	11.00%
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			3	1
Customer Concentration Risk | Accounts Receivable | Total Customers And Their Subcontractors
Accounting Policies [Line Items]
Number of major customers | customer			5
Customer Concentration Risk | Accounts Receivable | Major Customer One And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			16.00%
Customer Concentration Risk | Accounts Receivable | Major Customer Two And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			14.00%
Customer Concentration Risk | Accounts Receivable | Major Customer Three And Their Subcontractors
Accounting Policies [Line Items]
Percentage of concentration risk			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%	13.00%
Customer Concentration Risk | Accounts Receivable | Customer Two
Accounting Policies [Line Items]
Percentage of concentration risk				10.00%
Customer Concentration Risk | Accounts Receivable | Customer Three
Accounting Policies [Line Items]
Percentage of concentration risk				10.00%
Cork Ireland Building
Accounting Policies [Line Items]
Assets held for sale				$ 1,447,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Cork, Ireland And Alliance Building And Certain Machinery And Equipment
Accounting Policies [Line Items]
Cash proceeds		$ 3,078,000
Disposal group, gain (loss) of disposal or impairment of operating assets		1,545,000		$ 0
Other receivables, net		$ 2,447,000