Derivative, Notional Amount of Terminated Derivatives

No definition available.

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- Definition

Derivative, Number of Instruments Terminated

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Represents the amount of accrued interest and unused commitment fee payable as of the balance sheet date.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Represents the period that the credit facility may be extended under certain circumstances.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Number of extensions of a contract.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Number of mortgage loan agreements entered into during the period.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Payment of Derivative Fees and Accrued Interest

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Proceeds From Termination Payments, Net Of Fees

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of debts paid off during the period.

+ References

No definition available.

+ Details

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

- Definition

Amount of accumulated amortization of debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fee that accompanies borrowing money under the debt instrument.

+ References

+ Details

Name:	us-gaap_DebtInstrumentFeeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow from the repayment of a long-term debt instrument issued, secured by a first mortgage deed of trust, containing a pledge of real property. The lender has the highest claim on the property in case of default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The fair value of transfer of mortgage payable in noncash investing or financing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
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+ Details

Name:	us-gaap_TransferMortgagePayable
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

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- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=cmct_UnsecuredCreditFacilitySeptember2014TermLoanMember
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- Details

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DEBT - Narrative (Details)										1 Months Ended				12 Months Ended
DEBT - Narrative (Details)	Dec. 15, 2017 USD ($)	Nov. 29, 2017 USD ($) swap	Sep. 21, 2017 USD ($)	Aug. 03, 2017 USD ($) swap	Jun. 23, 2017 USD ($)	May 30, 2017 USD ($)	Mar. 28, 2017 USD ($)	Sep. 01, 2015 USD ($) swap	Apr. 01, 2015 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2016 USD ($) agreement	May 31, 2015 USD ($)	Sep. 30, 2014 USD ($) extension_option	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Aug. 31, 2017 USD ($)	Nov. 02, 2015 USD ($)
Debt
Deferred loan costs, gross														$ 3,843,000	$ 7,122,000
Deferred loan costs, accumulated amortization														1,105,000	1,818,000
Number of swaps terminated \| swap		4		3
Notional amount of terminated swaps		$ 150,000,000		$ 65,000,000
Proceeds from termination payments, net of fees														1,011,000
Payment of derivative fees and accrued interest														38,000
Payment of mortgages payable														65,877,000	4,354,000	$ 77,056,000
Accrued interest and unused commitment fee payable														2,098,000	3,133,000
Unsecured credit facility entered into in September 2014
Debt
Maximum borrowing capacity													$ 850,000,000
Number of extension options \| extension_option													2
Line of credit facility extension option term													1 year
Extension fee																	$ 300,000
Long-term Line of Credit														0	0
Amount available for future borrowings														97,000,000	200,000,000
Unsecured credit facility entered into in September 2014, revolver
Debt
Maximum borrowing capacity													$ 450,000,000	200,000,000
Unsecured credit facility entered into in September 2014, revolver \| Minimum
Debt
Unused commitment fee													0.15%
Unsecured credit facility entered into in September 2014, revolver \| Maximum
Debt
Unused commitment fee													0.25%
Unsecured credit facility entered into in September 2014, revolver \| LIBOR \| Minimum
Debt
Interest rate margin													1.20%
Unsecured credit facility entered into in September 2014, revolver \| LIBOR \| Maximum
Debt
Interest rate margin													2.00%
Unsecured credit facility entered into in September 2014, revolver \| Base rate \| Minimum
Debt
Interest rate margin													0.20%
Unsecured credit facility entered into in September 2014, revolver \| Base rate \| Maximum
Debt
Interest rate margin													1.00%
Unsecured credit facility entered into in September 2014, term loan
Debt
Maximum borrowing capacity													$ 325,000,000
Unsecured credit facility entered into in September 2014, term loan \| LIBOR \| Minimum
Debt
Interest rate margin													1.15%
Unsecured credit facility entered into in September 2014, term loan \| LIBOR \| Maximum
Debt
Interest rate margin													1.95%
Unsecured credit facility entered into in September 2014, term loan \| Base rate \| Minimum
Debt
Interest rate margin													0.15%
Unsecured credit facility entered into in September 2014, term loan \| Base rate \| Maximum
Debt
Interest rate margin													0.95%
Unsecured credit facility entered into in September 2014, delayed-draw term loan
Debt
Maximum borrowing capacity													$ 75,000,000
Unused commitment fee													0.25%
Mortgages payable
Debt
Number of mortgage loan agreements entered into \| agreement											6
Amount of loan											$ 392,000,000
Mortgages paid off \| swap								2
Unsecured Term Loan Facility Entered Into May 2015
Debt
Deferred loan costs, accumulated amortization		512,000		193,000
Maximum borrowing capacity												$ 385,000,000
Unused commitment fee												0.20%
Amount of loan														$ 170,000,000	$ 385,000,000			$ 385,000,000
Interest rate														2.96%	2.22%
Fixed interest rate														3.16%
Repayments of debt		150,000,000		65,000,000
Write off of deferred loan costs		$ 1,387,000		$ 601,000
Unsecured Term Loan Facility Entered Into May 2015 \| LIBOR \| Minimum
Debt
Interest rate margin												1.60%
Unsecured Term Loan Facility Entered Into May 2015 \| LIBOR \| Maximum
Debt
Interest rate margin												2.25%
Unsecured Term Loan Facility Entered Into May 2015 \| Base rate \| Minimum
Debt
Interest rate margin												0.60%
Unsecured Term Loan Facility Entered Into May 2015 \| Base rate \| Maximum
Debt
Interest rate margin												1.25%
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Debt
Payment of mortgages payable								$ 58,873,000	$ 12,364,000
Disposal Group, Held-for-sale, Not Discontinued Operations \| Mortgage loans with a fixed interest rate of 4.14% per annum, with monthly payments of interest only, and balances totaling $370,300,000 due on July 1, 2026. The loans are nonrecourse. In September 2017, one loan with an outstanding principal balance of $21,700,000 was assumed by the buyer in connection with the sale of the property that was collateral for the loan (Note 3).
Debt
Mortgage assumed by buyer										$ 21,700,000
211 Main Street, San Francisco, CA \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Debt
Payment of mortgages payable							$ 25,331,000
Mortgage prepayment penalty							$ 1,508,000
3636 McKinney Avenue and 3839 McKinney Avenue, Dallas, Texas \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Debt
Payment of mortgages payable						$ 15,448,000
Mortgage prepayment penalty						$ 1,901,000
4649 Cole Avenue, Dallas, TX \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Debt
Payment of mortgages payable					$ 23,333,000
Mortgage prepayment penalty					$ 2,812,000
7083 Hollywood Boulevard \| Disposal Group, Held-for-sale, Not Discontinued Operations
Debt
Mortgage assumed by buyer			$ 21,700,000
4200 Scotland Street, Houston, TX \| Disposal Group, Held-for-sale, Not Discontinued Operations
Debt
Mortgage assumed by buyer	$ 28,560,000