Summary of Significant Accounting Policies - Summary of Change in Allowance for Credit Losses (Details) $ in Thousands	6 Months Ended
Mar. 31, 2022 USD ($)
Receivables [Abstract]
Beginning balance	$ 879
Credit loss provision	(431)
Write-offs, net of recoveries	14
Foreign exchange impact on ending balance	(42)
Ending balance	$ 420

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