Name:	chrs_AccruedMilestonePayment
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Maximum aggregate milestone payments to be made

No definition available.

Name:	chrs_CollaborationAgreementMaximumAggregateMilestonePaymentsToBeMade
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Represents the percentage of royalty on net sales under the collaboration agreement.

No definition available.

Name:	chrs_CollaborationAgreementPercentageOfRoyaltyOnNetSales
Namespace Prefix:	chrs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Renewal term of agreement.

No definition available.

Name:	chrs_CollaborationAgreementRenewalTerm
Namespace Prefix:	chrs_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of regulatory and sales milestones eligible to receive under the collaborative arrangement.

No definition available.

Name:	chrs_CollaborativeArrangementRegulatoryAndSalesMilestonesEligibleToReceive
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The upfront payment received by the company under the collaborative arrangement.

No definition available.

Name:	chrs_CollaborativeArrangementUpfrontPaymentReceived
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount per each installment of milestone payments under collaborative arrangements.

No definition available.

Name:	chrs_MilestonePaymentsAmountPerEachInstallment
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Clinical payment associated with milestone based license fee payment.

No definition available.

Name:	chrs_MilestonePaymentsPaidForLicenseFee
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of regulatory milestones eligible to pay.

No definition available.

Name:	chrs_RegulatoryMilestonesEligibleToPay
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Carrying value as of the balance sheet date of obligations incurred through that date and payable for royalties.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(15)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Name:	us-gaap_AccruedRoyaltiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 808
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479402/808-10-50-1

Name:	us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Period Type:	duration

Name:	us-gaap_TypeOfArrangementAxis=chrs_JunshiBiosciencesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_BalanceSheetLocationAxis=chrs_IntangibleAssetsNetAndAccruedAndOtherCurrentLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=chrs_CanadaLicenseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: