Revenue - Additional Information (Details) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) contract unit	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) contract
Revenue from Contract with Customer [Abstract]
Number of units installed (over) \| unit	1,100
Unbilled receivables, current	$ 1,886		$ 1,857
Contract liabilities	497		$ 712
Revenue recognized, included in contract liability balance	$ 248	$ 224
Number of contracts identified as loss contracts \| contract	3		3
Provision for losses on contracts	$ 29		$ 26

Contract With Customer, Contracts In Progress, Number Of Contracts Identified As Loss Contracts

No definition available.

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- Definition

Number Of Units Installed

+ References

No definition available.

+ Details

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

+ Details

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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

+ Details

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- Definition

Cumulative provision for contract losses not offset against related costs accumulated on the balance sheet.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57777-111642

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- References

No definition available.

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- Definition

Amount received for services rendered and products shipped, but not yet billed, for non-contractual agreements due within one year or the normal operating cycle, if longer.

+ References

No definition available.

+ Details

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