Aggregate collaboration transaction amount.

No definition available.

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- Definition

Common stock shares issuable under agreement.

+ References

No definition available.

+ Details

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- Definition

Future contingent milestone payment receivable.

+ References

No definition available.

+ Details

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- Definition

Contingent payments payable upon achieving development regulatory and commercial milestones.

+ References

No definition available.

+ Details

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- Definition

Estimated fair value of products.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

Estimated research service period.

+ References

No definition available.

+ Details

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- Definition

License payment percentage equivalence to upfront and milestone proceeds.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Number of additional collaboration target.

+ References

No definition available.

+ Details

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- Definition

Number of targets.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
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- Definition

Number of targets selected.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
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- Definition

Premium on issuance of shares allocated to common stock.

+ References

No definition available.

+ Details

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Namespace Prefix:	ctmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479402/808-10-50-1

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Cash received from collaborators during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from the additional capital contribution to the entity.

+ References

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-Paragraph 14
-Subparagraph (a)
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Balance Type:	debit
Period Type:	duration

- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 606
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Data Type:	xbrli:monetaryItemType
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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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Collaboration and License Agreements - Amgen, Inc - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Sep. 29, 2017 USD ($) Target	May 31, 2025 USD ($)	Oct. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, value of shares issued in connection with agreement		$ 93,400		$ 109,635	$ 6,909
Deferred revenue				$ 28,467	94,063	$ 212,315
Collaboration and License Agreement \| Amgen Inc
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received	$ 40,000		$ 40,000
Common stock, shares issuable under agreement \| shares			1,156,069
Common stock, shares issuable under agreement, price per share \| $ / shares			$ 17.3
Common stock, value of shares issued in connection with agreement			$ 20,000
Number of targets selected \| Target	1
Number of additional collaboration target \| Target	2
Total transaction price	$ 51,200
Portion of transaction price allocated to premium on sale of common stock	500
Estimated fair value of products	10,700
Collaboration and License Agreement \| Amgen Inc \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payments payable	203,000
Collaboration and License Agreement \| Amgen Inc \| EGFR Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total transaction price	46,400
Deferred revenue					$ 9,700
Collaboration and License Agreement \| Amgen Inc \| EGFR Products \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent milestone payments receivable	$ 460,000
Collaboration and License Agreement \| Amgen Inc \| Amgen Products \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets \| Target	3
Collaboration and License Agreement \| Amgen Inc \| Amgen Other Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total transaction price	$ 4,800
Estimated research service period	6 years
Revenue recognition upon performance obligation	$ 4,800
Sublicense Agreement \| Amgen Inc \| Maximum \| UC Regents
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Sublicense payment percentage	7.50%