Leases - Additional Information (Details)	1 Months Ended				3 Months Ended	9 Months Ended
	Apr. 30, 2020 USD ($)	Apr. 30, 2020 CNY (¥)	Nov. 30, 2019 USD ($) m²	Nov. 30, 2019 CNY (¥) m²	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Aug. 27, 2020 USD ($)	Aug. 27, 2020 CNY (¥)	Dec. 31, 2019 USD ($)
Weighted average remaining lease term					36 years 4 months 9 days	36 years 4 months 9 days
Weighted average discount rates					4.20%	4.20%
Rent expenses						$ 1,153,000	$ 957,000
Right of use assets					$ 9,015,000	9,015,000				$ 8,708,000
Lease liability					$ 2,363,000	2,363,000				$ 2,201,000
CHINA
Number of lease agreements					2
Right of use assets					$ 1,100,000	1,100,000
Lease liability					$ 1,000,000.0	$ 1,000,000.0
Term of the lease contract					3 years	3 years
CASI Wuxi [Member]
Construction project contract amount								$ 10,923,000	¥ 74,588,000
Term of the lease contract			50 years	50 years
Land parcel area (in square meters) | m²			74,028.40	74,028.40
Prepaid lease payments for the land use right			$ 6,600,000	¥ 45,000,000
Government grant received	$ 2,200,000	¥ 15,900,000