Concentration Risk, Number Of Properties Occupied

No definition available.

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

- Definition

Represents the number of states in which the entity owns real estate properties as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	cmct_NumberofStatesinwhichRealEstatePropertiesareOwned
Namespace Prefix:	cmct_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.5-02(3))
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Subparagraph (SX 210.7-03(5))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	cmct_InvestmentsInRealEstateTypeAxis=cmct_RealEstateOfficePropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cmct_InvestmentsInRealEstateTypeAxis=cmct_RealEstateHotelPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cmct_InvestmentsInRealEstateTypeAxis=cmct_RealEstateParkingGarageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cmct_InvestmentsInRealEstateTypeAxis=cmct_RealEstateDevelopmentSiteMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_SalesRevenueNetMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
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Balance Type:
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- Details

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- Details

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- Details

Name:	srt_MajorCustomersAxis=cmct_GovernmentalTenantsMember
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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_RealEstateInvestmentMember
Namespace Prefix:
Data Type:	na
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- Details

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CONCENTRATIONS (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
CONCENTRATIONS (Details) $ in Thousands	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 state	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 state	Dec. 31, 2019 USD ($) property
Concentration Risk [Line Items]
Number of states in which properties are owned \| state		2		2
Office properties
Concentration Risk [Line Items]
Number of real estate properties owned	8		8		8
Hotel properties
Concentration Risk [Line Items]
Number of real estate properties owned	1		1		1
Parking garages
Concentration Risk [Line Items]
Number of real estate properties owned	1		1		1
Development site
Concentration Risk [Line Items]
Number of real estate properties owned	1		1		1
Revenues \| Customer Concentration Risk \| Kaiser Foundation Health Plan, Inc.
Concentration Risk [Line Items]
Amounts due from tenant revenue concentrations \| $	$ 51		$ 51		$ 23
Revenues \| Customer Concentration Risk \| Kaiser Foundation Health Plan, Inc. \| California
Concentration Risk [Line Items]
Number of properties occupied by tenant revenue concentrations			2
Revenues \| Customer Concentration Risk \| Governmental Tenants
Concentration Risk [Line Items]
Amounts due from tenant revenue concentrations \| $	$ 3		$ 3		$ 282
Revenues \| Geographical concentrations
Concentration Risk [Line Items]
Concentration risk, percent	100.00%	100.00%	100.00%	100.00%
Revenues \| Geographical concentrations \| California
Concentration Risk [Line Items]
Concentration risk, percent	88.60%	84.10%	90.00%	77.70%
Revenues \| Geographical concentrations \| Texas
Concentration Risk [Line Items]
Concentration risk, percent	11.40%	7.40%	9.80%	5.10%
Revenues \| Geographical concentrations \| Washington, D.C.
Concentration Risk [Line Items]
Concentration risk, percent	0.00%	8.50%	0.20%	17.20%
Real Estate Investments \| Geographical concentrations
Concentration Risk [Line Items]
Concentration risk, percent			100.00%		100.00%
Real Estate Investments \| Geographical concentrations \| California
Concentration Risk [Line Items]
Concentration risk, percent			93.90%		94.40%
Real Estate Investments \| Geographical concentrations \| Texas
Concentration Risk [Line Items]
Concentration risk, percent			6.10%		5.60%
Office \| Revenues \| Customer Concentration Risk \| Kaiser Foundation Health Plan, Inc.
Concentration Risk [Line Items]
Concentration risk, percent	27.90%	22.20%	26.10%	15.60%
Office \| Revenues \| Customer Concentration Risk \| Governmental Tenants
Concentration Risk [Line Items]
Concentration risk, percent	2.50%	11.20%	2.30%	20.00%