The amount of carryback net operating losses.

No definition available.

Name:	cmmb_CarrybackNetOperatingLosses
Namespace Prefix:	cmmb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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_RestructuringCostAndReserveLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash received on stock transaction after deduction of issuance costs.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockConsiderationReceivedOnTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of consideration received by subsidiary or equity investee in exchange for shares of stock issued or sold. Includes amount of cash received, fair value of noncash assets received, and fair value of liabilities assumed by the investor.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockConsiderationReceivedPerTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_StatementClassOfStockAxis=cmmb_AmericanDepositorySharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=cmmb_AtMarketOfferingAgreementWithCantorFitzgeraldAndCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

General (Detail Textuals) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 22, 2023	Apr. 25, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Restructuring Cost and Reserve [Line Items]
Carryback net operating losses			$ 187	$ 351
American Depositary Share ("ADS") [Member]
Restructuring Cost and Reserve [Line Items]
Gross proceeds from sale under agreement	$ 10,000
American Depositary Share ("ADS") [Member] \| At The Market Offering Agreement With Cantor Fitzgerald & Co. [Member]
Restructuring Cost and Reserve [Line Items]
Aggregate offering price		$ 18,125,000	$ 75,000
Shares issued under agreement			699,806		130,505
Average price of shares issued under agreement			$ 22.75		$ 2.11
Gross proceeds from sale under agreement			$ 15,917		$ 275