Note 7 - Accrued Liabilities (Details Textual) $ in Millions	3 Months Ended
Jul. 31, 2016 USD ($)
Zheng Ge Electrical Company Ltd [Member]
Uninvoiced Materials and Services Received, Write-offs	$ 0.3

Amount of direct write-downs of uninvoiced materials and services received liabilities.

No definition available.

Name:	cmro_UninvoicedMaterialsAndServicesReceivedWriteoffs
Namespace Prefix:	cmro_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration