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Summary of Significant Accounting Policies - Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Summary of Significant Accounting Policies
Research and development	$ 163,550	$ 118,011	$ 82,258
Single reportable segment
Summary of Significant Accounting Policies
Research and development	163,550	118,011	82,258
Single reportable segment | Barzolvolimab/Anti-KIT Program
Summary of Significant Accounting Policies
Research and development	123,750	79,913	51,220
Single reportable segment | CDX-622
Summary of Significant Accounting Policies
Research and development	17,341	16,299	5,613
Single reportable segment | CDX-585
Summary of Significant Accounting Policies
Research and development	2,813	6,357	9,793
Single reportable segment | Other Programs (a)
Summary of Significant Accounting Policies
Research and development	$ 19,646	$ 15,442	$ 15,632

X

- Definition

Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 730
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482916/730-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 912
-SubTopic 730
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479532/912-730-25-1

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