Basis of Presentation, Organization and Principal Activities - Basis of Presentation (Details)	6 Months Ended
Jun. 30, 2021 segment
Description of Business and Basis of Presentation
Number of operating segments	1
CASI China
Description of Business and Basis of Presentation
Percentage of ownership interest held by the parent entity in the non stock subsidiary	100.00%
CASI Wuxi
Description of Business and Basis of Presentation
Percentage of ownership interest held by the parent entity in the non stock subsidiary	80.00%

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

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