Call option purchase investment period.

No definition available.

Name:	casi_CallOptionToPurchaseInvestmentPeriod
Namespace Prefix:	casi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Initial cash investment.

+ References

No definition available.

+ Details

Name:	casi_InitialCashInvestment
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represent the investment commitment.

+ References

No definition available.

+ Details

Name:	casi_InvestmentCommitment
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the committed amount of cash payment within three years from the date of establishment of CASI Wuxi.

+ References

No definition available.

+ Details

Name:	casi_PaymentsToBePaidWithinThreeYears
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Payments to be made in the current fiscal year relating to the investments in redeemable noncontrolling interest.

+ References

No definition available.

+ Details

Name:	casi_RedeemableNoncontrollingInterestCurrentPaymentToBeMade
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of installments in which payments should be made relating to the investments in redeemable noncontrolling interest.

+ References

No definition available.

+ Details

Name:	casi_RedeemableNoncontrollingInterestNumberOfPaymentInstallments
Namespace Prefix:	casi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Payments to be made in next twelve months from the fiscal year following current fiscal year relating to the investments in redeemable noncontrolling interest.

+ References

No definition available.

+ Details

Name:	casi_RedeemableNoncontrollingInterestPaymentToBeMadeInNextTwelveMonths
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Payments to be made in second fiscal year following current fiscal year relating to the investments in redeemable noncontrolling interest.

+ References

No definition available.

+ Details

Name:	casi_RedeemableNoncontrollingInterestPaymentToBeMadeInYearTwo
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represent the selected and as to be transferred.

+ References

No definition available.

+ Details

Name:	casi_SelectedAndasToBeTransferred
Namespace Prefix:	casi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
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_MinorityInterestLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the purchase of all investments (debt, security, other) during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=casi_CASIWuxiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=us-gaap_CallOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=us-gaap_PutOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=casi_CASIWuxiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Redeemable Noncontrolling Interest (Details) $ in Millions	1 Months Ended		6 Months Ended
Redeemable Noncontrolling Interest (Details) $ in Millions	May 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jun. 30, 2021 USD ($) installment	Feb. 28, 2019 USD ($)	Dec. 26, 2018 USD ($)
Noncontrolling Interest
Equity ownership (as a percent)			8.30%
Value of transfer of selected ANDAs			$ 30
CASI Wuxi
Noncontrolling Interest
Equity ownership (as a percent)					80.00%
Investment commitment					$ 80
Initial cash investment				$ 21
Value of transfer of selected ANDAs	$ 30
Committed amount of cash payment within three years			$ 29
Call option purchase investment period			5 years
Payments to acquire investments		$ 20	$ 20
Number of installments \| installment			3
Payments to be made in the current fiscal year			$ 10
Payments to be made in 2022			10
Payments to be made in 2023			$ 9
CASI Wuxi \| Call Option
Noncontrolling Interest
Equity ownership (as a percent)			20.00%
CASI Wuxi \| Put option
Noncontrolling Interest
Equity ownership (as a percent)			20.00%
CASI Wuxi
Noncontrolling Interest
Payments to acquire investments			$ 20