BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment (Details) - property	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of types of commercial real estate properties	2	2	2

Represents the number of types of commercial real estate properties.

No definition available.

Name:	cmct_NumberOfTypesOfCommercialRealEstateProperties
Namespace Prefix:	cmct_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration