Cost Reduction Actions - Details of Future Cash Payments (Details) - USD ($)	Jul. 31, 2015	Jul. 31, 2014	Oct. 31, 2008	Jul. 31, 2008
Radyne Acquisition Related Restructuring Plan [Abstract]
Future lease payments to be made in excess of anticipated sublease payments	$ 4,235,000	$ 3,773,000	$ 2,100,000	$ 2,100,000
Interest expense to be accreted in future periods	678,000
Total remaining net cash payments	$ 4,913,000

Amount accrued to cover estimated present value of facility exit costs related to noncancellable lease obligations assumed in a business combination, net of the present value of estimated sublease income.

No definition available.

Name:	cmtl_BusinessAcquisitionRestructuringCostsFacilityRelatedExitCosts
Namespace Prefix:	cmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant