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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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