Fair Value Measurements and Financial Instruments (Details)	Oct. 31, 2017
Fair Value Disclosures [Abstract]
Non-current portion of capital lease obligations, a blended interest rate (percent)	5.90%

A blended interest rate of non-current portion of capital lease obligations

No definition available.

Name:	cmtl_CapitalLeaseObligationsNoncurrentABlendedInterestRate
Namespace Prefix:	cmtl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant