Debt - Expected Principal, Interest and Fee Payments on Term Loan Credit Agreement (Detail) - Term Loan Credit Agreement - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
2023, Principal	$ 41,250
2024, Principal	13,750
Total, Principal	55,000	$ 55,000
2022 Interest and Fees	2,097
2023, Interest and Fees	3,134
2024, Interest and Fees	1,826
Total, Interest and Fees	7,057
2022 Total	2,097
2023, Total	44,384
2024, Total	15,576
Total	$ 62,057

Long term debt maturities repayments of interest and fees.

No definition available.

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

- Definition

Long term debt maturities repayments of interest and fees in remainder of fiscal year.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of interest and fees in year three.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of interest and fees in year two.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of principal and interest.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of principal and interest in remainder of fiscal year.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of principal and interest in year three.

+ References

No definition available.

+ Details

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

- Definition

Long term debt maturities repayments of principal and interest in year two.

+ References

No definition available.

+ Details

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

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: 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))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1E
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123465755&loc=d3e1835-112601

+ Details

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

- Definition

Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Details

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