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Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Revenue from External Customer [Line Items]
Cash equivalents, qualification, maximum original maturity of short-term investments										3 months
Customer deposit requirements, large custom contracts, maximum percentage										50.00%
Allowance for doubtful accounts	$ 918,000				$ 291,000					$ 918,000	$ 291,000
Revenues	19,706,000	$ 20,852,000	$ 19,895,000	$ 17,991,000	16,160,000	$ 16,396,000	$ 18,204,000	$ 14,718,000		78,444,000	65,478,000	$ 67,693,000
Revenue recognized										48,000	176,000
Impairments		10,000,000.0								10,039,000	0	0
Product warranty reserves	74,000				22,000					74,000	22,000
Uncertain tax positions	0									$ 0
Number of business segments | segment										1
Right of use assets	604,000				0					$ 604,000	0		$ 451,000
Operating lease, liability	$ 604,000				0					604,000	0		451,000
Operating costs and expenses										$ 93,597,000	65,985,000	66,222,000
Minimum
Revenue from External Customer [Line Items]
Rental arrangements, original term										6 months
Maximum
Revenue from External Customer [Line Items]
Rental arrangements, original term										60 months
Revisions | Revision Of Prior Period Financial Statements
Revenue from External Customer [Line Items]
Revenues		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0			0	0
Operating costs and expenses									$ 1,100,000		1,145,000	$ 96,000
Developed Technology
Revenue from External Customer [Line Items]
Intangible assets, useful life										20 years
Intangible assets, weighted average remaining life										5 years
Bill and Hold Arrangement
Revenue from External Customer [Line Items]
Revenues										$ 11,600,000	$ 8,300,000
Accounting Standards Update 2016-02
Revenue from External Customer [Line Items]
Right of use assets													451,000
Operating lease, liability													$ 451,000
Accounts Receivable | Customer Concentration Risk
Revenue from External Customer [Line Items]
Concentration risk, percentage										35.00%	26.00%

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