Trade and Other Receivables (Narrative) (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Trade and other current receivables [abstract]
Number of monthly payments (mainly)	36
Annual discount rate	3.30%	3.30%

Annual discount rate on non-current trade receivables.

No definition available.

Name:	cel_AnnualDiscountRateOnNonCurrentTradeReceivables
Namespace Prefix:	cel_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant