Standard Product Warranty, Number of Years

No definition available.

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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Amount of loss from impairment of right-of-use asset from operating lease.

+ References

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-Name Accounting Standards Codification
-Topic 842
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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

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- Definition

Amount of expense (reversal of expense) which increases (decreases) the restructuring reserve from an adjustment to a previously accrued restructuring liability.

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Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended		12 Months Ended
	Apr. 01, 2016	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jan. 01, 2019
Concentration Risk [Line Items]
Operating lease liabilities		$ 1,741			$ 1,741
Operating lease right-of-use assets		$ 1,541			$ 1,541
Operating lease, impairment loss			$ 186
Securities excluded from net loss per share calculation (in shares)		28		87	66	83
Warranty service periods	10 years
Minimum
Concentration Risk [Line Items]
Warranty service periods					1 year
Maximum
Concentration Risk [Line Items]
Warranty service periods					5 years
Geographic concentration risk \| United States
Concentration Risk [Line Items]
Concentration risk (less than for one percent)					97.00%
Revenue \| Geographic concentration risk \| Countries outside of the United States
Concentration Risk [Line Items]
Concentration risk (less than for one percent)		0.00%		5.00%	1.00%	3.00%
Distributor To The U.S. Navy \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)		13.00%		29.00%	17.00%	37.00%
Distributor To The U.S. Navy \| Accounts receivable \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)					13.00%		40.00%
Global Healthcare Systems, Northeast Ohio [Member] \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				15.00%		12.00%
Commercial Lighting Retrofit Company \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)		26.00%		11.00%	28.00%
Commercial Lighting Retrofit Company \| Accounts receivable \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)					26.00%
U.S. Navy \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)		20.00%		33.00%	26.00%	41.00%
Accounting Standards Update 2016-02
Concentration Risk [Line Items]
Operating lease liabilities								$ 2,900
Operating lease right-of-use assets								$ 2,900
Facilities \| 2017 Restructuring Plan
Concentration Risk [Line Items]
Reclassification upon adoption of Topic 842			$ 273