Significant Accounting Policies - Summary of Change in Allowance for Credit Losses (Details) $ in Thousands	9 Months Ended
Jun. 30, 2025 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 1,614
Credit loss provision	208
Write-offs, net of recoveries	(1,745)
Effect of foreign currency translation	(9)
Ending balance	$ 68

Accounts receivable and contract with customer assets allowance for credit loss

No definition available.

Name:	crnc_AccountsReceivableAndContractWithCustomerAssetsAllowanceForCreditLoss
Namespace Prefix:	crnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Accounts receivable and contract with customer assets allowance for credit loss effect of foreign currency translation.

No definition available.

Name:	crnc_AccountsReceivableAndContractWithCustomerAssetsAllowanceForCreditLossEffectOfForeignCurrencyTranslation
Namespace Prefix:	crnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Accounts receivable and contract with customer assets allowance for credit loss (write-offs) net of recoveries.

No definition available.

Name:	crnc_AccountsReceivableAndContractWithCustomerAssetsAllowanceForCreditLossWriteOffsNetOfRecoveries
Namespace Prefix:	crnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Accounts receivable and contract with customer assets provision for credit loss.

No definition available.

Name:	crnc_AccountsReceivableAndContractWithCustomerAssetsProvisionForCreditLoss
Namespace Prefix:	crnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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