Significant Accounting Policies - Additional Information (Details) $ in Millions	6 Months Ended
Mar. 31, 2020 USD ($)
Accounting Policies [Abstract]
Deferred rent reclassified as right of use assets	$ 2.2

Deferred rent reclassified as right of use assets.

No definition available.

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