REVENUES - Unearned Revenues (Details)	12 Months Ended
Dec. 29, 2019
REVENUES
Subscribers advance payment term (in years)	1 year
Advertiser maximum payment (in days)	30 days

Period of time for advertiser maximum payment in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	mni_ContractWithCustomerAdvertiserMaximumPaymentDueDuration
Namespace Prefix:	mni_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration