Prepaid (Details) - Schedule of prepaid expenses - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule of prepaid expenses [Abstract]
Prepaid products and services	$ 6,475	$ 172
Deferred offering expenses		569
Prepaid rent and security deposit	259	732
Prepaid expenses, net	$ 6,734	$ 1,473

Amount of asset related to consideration paid in advance for services that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

No definition available.

+ Details

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Namespace Prefix:	coms_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of asset related to consideration paid in advance for rent and security deposit that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

+ References

No definition available.

+ Details

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Namespace Prefix:	coms_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Specific incremental costs directly attributable to a proposed or actual offering of securities which are deferred at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.A)
-URI http://asc.fasb.org/extlink&oid=122040515&loc=d3e105025-122735

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of expenditures made in advance of when the economic benefit of the cost will be realized, and which will be expensed in future periods with the passage of time or when a triggering event occurs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.10)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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Balance Type:	debit
Period Type:	instant