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Concentrations of Credit Risk (Details) - item	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Revenue | Customer | Customer 1
Concentrations of Credit Risk
Number of major customers	1	1

X

- Definition

Represents the number of major customers.

+ References

No definition available.

+ Details

Name:	cert_NumberOfMajorCustomers
Namespace Prefix:	cert_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- 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.

+ Details

Name:	us-gaap_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_RevenueFromContractWithCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_MajorCustomersAxis=cert_Customer1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: