Amount of debt instrument repurchase of guaranteed amount.

No definition available.

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Namespace Prefix:	cmtg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of short-term bank loan secured by broker-dealer customer's security.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

+ Details

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Namespace Prefix:	srt_
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

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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

- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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

- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- 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

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Data Type:	xbrli:stringItemType
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- Details

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Repurchase Agreements, Loan Participations Sold, Net, Notes Payable, Net, Secured Term Loan, Net and Debt Related to Real Estate Owned, Net - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 02, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Feb. 08, 2021	Dec. 01, 2020	Aug. 09, 2019
Repurchase Agreement Counterparty [Line Items]
Secured term loan								$ 325,000,000.0	$ 450,000,000.0
Interest expense		$ 48,070,000	$ 39,740,000	$ 151,188,000	$ 129,081,000
General and administrative expenses		1,330,000	$ 1,169,000	$ 5,393,000	$ 4,162,000
Secured Term Loan
Repurchase Agreement Counterparty [Line Items]
Principal payments						$ 1,900,000
Contractual Maturity Date				Aug. 09, 2026		Aug. 09, 2026
Repurchase Agreements
Repurchase Agreement Counterparty [Line Items]
Debt instrument repurchase guaranteed amount		$ 786,500,000		$ 786,500,000		$ 701,300,000
Real Estate Investment
Repurchase Agreement Counterparty [Line Items]
Principal payments	$ 10,000,000.0
Senior mortgage amount							$ 300,000,000.0
Contractual Maturity Date	Feb. 09, 2024
Debt instrument, Fee amount	$ 7,600
Interest expense	6,300,000
General and administrative expenses	1,100,000
Debt issuance costs	$ 200,000