Leases (Narrative) (Details) ₪ in Millions	12 Months Ended
Dec. 31, 2020 ILS (₪)
Presentation of leases for lessee [abstract]
Increase decrease in lease liability	₪ 289

The increase (decrease) in amount of lease liability.

No definition available.

Name:	cel_IncreaseDecreaseInLeaseLiability
Namespace Prefix:	cel_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration