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

Represents co-development, regulatory and technology transfer costs.

No definition available.

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

Amount of additional clinical milestones eligible to receive

No definition available.

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

Additional payment to be made

No definition available.

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

Maximum aggregate milestone payments to be made

No definition available.

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

Collaboration Agreement , Maximum Payments On Attainment Of Certain Sales Thresholds

No definition available.

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

The amount of maximum payments to be made on attainment of certain sales thresholds for each option program under the collaboration agreement.

No definition available.

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

Amount of milestone payments earned

No definition available.

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

Number of undisclosed preclinical immuno-oncology drug candidates under the collaboration agreement.

No definition available.

Name:	chrs_CollaborationAgreementNumberOfUndisclosedPreclinicalImmunoOncologyDrugCandidates
Namespace Prefix:	chrs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The amount of option exercise fee per program under the collaboration agreement.

No definition available.

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

Represents the percentage of royalty on net sales for each option program under the collaboration agreement.

No definition available.

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

Period for payment of nominal research maintenance fee

No definition available.

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

Amount of regulatory milestones eligible to receive

No definition available.

Name:	chrs_CollaborationAgreementRegulatoryMilestonesEligibleToReceive
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Term of agreement

No definition available.

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

The amount of threshold payments to be made on achievement on various milestones for each option program under the collaboration agreement.

No definition available.

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

Represents costs associated to a collaboration agreement.

No definition available.

Name:	chrs_CollaborationCosts
Namespace Prefix:	chrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 of decrease in research and development expenses for release of certain liabilities.

No definition available.

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

Represents the maximum paid amount for co-development activities.

No definition available.

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

Maximum antibodies partially exercised under commercialization option

No definition available.

Name:	chrs_MaximumAntibodiesPartiallyExericsedUnderCommercializationOption
Namespace Prefix:	chrs_
Data Type:	xbrli:integerItemType
Balance Type:	na
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
Period Type:	duration

The cash outflow 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

Minimum antibodies to be commercialized under commercialization option

No definition available.

Name:	chrs_MinimumAntibodiesToBeCommercializedUnderCommercializationOption
Namespace Prefix:	chrs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

percentage of profit shared.

No definition available.

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

Percentage of option fee to be paid on partial exercise of commercialization option

No definition available.

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

Percentage of royalties incurred on net sales.

No definition available.

Name:	chrs_PercentageOfRoyaltiesOnNetSales
Namespace Prefix:	chrs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

Amount of sales milestones entitled.

No definition available.

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

Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 730
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482916/730-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 912
-SubTopic 730
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479532/912-730-25-1

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

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

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

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

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

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

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_BalanceSheetLocationAxis=chrs_AccruedAndOtherCurrentLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	srt_ProductOrServiceAxis=us-gaap_LicenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_ProductOrServiceAxis=chrs_ToripalimabMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=chrs_Chs006AntiTigitAntibodyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_ProductOrServiceAxis=chrs_AntiTigitAntibodyAndIl2CytokineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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