Debt instrument, available amount upon condition.

No definition available.

Name:	cers_DebtInstrumentAvailableAmountUponCondition
Namespace Prefix:	cers_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument interest only payments due period.

+ References

No definition available.

+ Details

Name:	cers_DebtInstrumentInterestOnlyPaymentsDuePeriod
Namespace Prefix:	cers_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument interest only payments extended period.

+ References

No definition available.

+ Details

Name:	cers_DebtInstrumentInterestOnlyPaymentsExtendedPeriod
Namespace Prefix:	cers_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument principal and declining interest payments additional period.

+ References

No definition available.

+ Details

Name:	cers_DebtInstrumentPrincipalAndDecliningInterestPaymentsAdditionalPeriod
Namespace Prefix:	cers_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of equal tranches.

+ References

No definition available.

+ Details

Name:	cers_NumberOfEqualTranches
Namespace Prefix:	cers_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=cers_PriorTermLoanCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=cers_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cers_TrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cers_TrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cers_TrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cers_TermLoanCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=cers_FloorRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cers_TrancheFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cers_PriorRevolvingLoanCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Detail)		3 Months Ended
Debt - Additional Information (Detail)	Mar. 29, 2019 USD ($) Tranche	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Prior Term Loan Credit Agreement
Debt Instrument [Line Items]
Term loan, face amount	$ 70,000,000
Number of loan tranches \| Tranche	3
Debt instrument maturity date	Mar. 01, 2024
Prior Term Loan Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Debt instrument floating interest rate percentage	1.80%
Prior Term Loan Credit Agreement \| Tranche 1
Debt Instrument [Line Items]
Term loan, face amount	$ 40,000,000.0	$ 40,000,000.0
Prior Term Loan Credit Agreement \| Tranche 2 \| Term Loan
Debt Instrument [Line Items]
Term loan, face amount	$ 15,000,000.0	15,000,000.0
Prior Term Loan Credit Agreement \| Tranche 3 \| Term Loan
Debt Instrument [Line Items]
Debt instrument maturity date	Dec. 31, 2021
Loan and security agreement available upon revenue achievement	$ 15,000,000.0
Term Loan Credit Agreement
Debt Instrument [Line Items]
Term loan, face amount		$ 75,000,000.0
Term Loan Credit Agreement \| SOFR
Debt Instrument [Line Items]
Variable rate		6.50%
Term Loan Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Effective interest rate		11.30%
Debt instruments, interest only payments due		36 months
Principal plus declining interest payments		24 months
Debt instrument interest only payments extended period		12 months
Term Loan Credit Agreement \| Tranche 1 \| Floor
Debt Instrument [Line Items]
Variable rate		1.00%
Term Loan Credit Agreement \| Tranche 2 \| Floor
Debt Instrument [Line Items]
Variable rate		1.00%
Term Loan Credit Agreement \| Tranche 3 \| Floor
Debt Instrument [Line Items]
Variable rate		1.00%
Term Loan Credit Agreement \| Tranche 3 \| Term Loan
Debt Instrument [Line Items]
Loan and security agreement available upon revenue achievement		$ 10,000,000.0
Term Loan Credit Agreement \| Tranche 4 \| Floor
Debt Instrument [Line Items]
Variable rate		1.00%
Term Loan Credit Agreement \| Tranche 4 \| Term Loan
Debt Instrument [Line Items]
Loan and security agreement available upon revenue achievement		$ 10,000,000.0
Prior Revolving Loan Credit Agreement
Debt Instrument [Line Items]
Loan and security agreement available upon revenue achievement		5,000,000.0
Borrowing limit		$ 15,000,000.0
Prior Revolving Loan Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Debt instrument maturity date		Mar. 01, 2024
Revolving Loan Credit Agreement
Debt Instrument [Line Items]
Term loan, face amount		$ 18,000,000.0	$ 14,900,000
Loan and security agreement available upon revenue achievement		15,000,000.0
Borrowing limit		$ 20,000,000.0
Revolving Loan Credit Agreement \| SOFR
Debt Instrument [Line Items]
Debt instrument floating interest rate percentage	0.10%
Variable rate		3.75%
Revolving Loan Credit Agreement \| Floor
Debt Instrument [Line Items]
Variable rate		1.00%