Amount of additional equity method investments purchased durign the year.

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

The maximum amount that can be borrowed by the related party borrower under the loans advanced by the company.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Amount of equal installments in which loan will be advanced to related party.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

The maximum amount that can be borrowed by the related party borrower under the loans advanced by the company.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Percentage of price per share issued at which outstanding principal loan advanced to related party is to be converted.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Term of the loan advanced to related party, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

Amount of minimum equity financing to be completed by the entity.

+ References

No definition available.

+ Details

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

- Definition

Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value portion of investments accounted under the equity method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=117311354&loc=d3e32014-111567

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Period Type:	instant

- Definition

Amount of interest income earned from interest-bearing assets owed to the entity by related party.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ 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
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

+ Details

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

- Definition

Identify the stated interest rate per the agreement, for example, leasing and debt arrangements between related parties.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=us-gaap_PutOptionMember
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Data Type:	na
Balance Type:
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- Details

Name:	casi_InvestmentsContractCounterpartyAxis=casi_BlackBeltTxLimitedMember
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Investment in Equity Securities, at fair value and long-term investments - Additional Information (Details)			1 Months Ended											3 Months Ended		9 Months Ended
	Sep. 29, 2020 USD ($)	Sep. 29, 2020 CNY (¥)	Sep. 30, 2020	Aug. 31, 2020 USD ($)	Aug. 31, 2020 CNY (¥)	Jul. 31, 2020 EUR (€)	Jul. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 CNY (¥)	Jun. 30, 2019 USD ($)	Jun. 30, 2019 CNY (¥)	Apr. 30, 2019 EUR (€)	Apr. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 29, 2020 CNY (¥)	Jul. 31, 2020 USD ($)
Change in fair value of investment in equity securities and long-term investments														$ 862,000	$ (160,000)	$ 1,171,000	$ (355,000)
Juventas Cell Therapy Ltd [Member]
Change in fair value of investment in equity securities and long-term investments														$ (1,116,000)		$ (1,116,000)
Payments to acquire Equity Investments										$ 11,788,000	¥ 80,000,000
Loans Advanced To Related Party, Term				1 year	1 year			1 year	1 year
Equity ownership (as a percent)			19.652%	20.00%	20.00%					16.327%	16.327%			19.652%		19.652%
Interest rate (as a percent)			8.00%					20.00%	20.00%	8.00%	8.00%
Additional equity investment \| ¥		¥ 70,000,000
Fair value of additional equity interest	$ 12,300,000																	¥ 83,700,000
Loans Advanced To Related Party				$ 5,790,000	¥ 40,000,000			$ 4,243,000	¥ 30,000,000
Interest Income, Related Party														$ 351,000		$ 375,000
Juventas Cell Therapy Ltd [Member] \| Put option
Payments to acquire Equity Investments	$ 64,000	¥ 400,000
Black Belt TX Limited [Member]
Payments to acquire Equity Investments												€ 2,000,000	$ 2,249,600
Amount of equal installments						€ 70,600	$ 83,000
Minimum Equity Financing Trigger						€ 5,000,000													$ 5,900,000
Percentage of price per share issued at which the outstanding principal loan is to be converted						80.00%	80.00%
Equity ownership (as a percent)												14.10%	14.10%
Interest rate (as a percent)						6.00%	6.00%
Loan to be advanced						€ 211,800	$ 250,000