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 date.

+ References

No definition available.

+ Details

Name:	cers_DebtInstrumentInterestOnlyPaymentsDate
Namespace Prefix:	cers_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument principal and declining interest payments additional period.

+ References

No definition available.

+ Details

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

- Definition

Number of equal tranches.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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+ 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.

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+ Details

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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

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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

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+ Details

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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.

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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.

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Period Type:	instant

- Details

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Balance Type:
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- Details

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- Details

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- Details

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Period Type:

Debt - Additional Information (Detail)	Mar. 29, 2019 USD ($) Tranche	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
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
Term Loan Credit Agreement \| Two Thousand Nineteen Term Loan
Debt Instrument [Line Items]
Debt instrument floating interest rate percentage	1.80%
Effective interest rate		7.50%
Interest-only payments date	Mar. 01, 2023
Principal plus declining interest payments	12 months
Term Loan Credit Agreement \| Tranche 1
Debt Instrument [Line Items]
Term loan, face amount	$ 40,000,000.0
Term Loan Credit Agreement \| Tranche 2 \| Two Thousand Nineteen Term Loan
Debt Instrument [Line Items]
Term loan, face amount	15,000,000.0
Term Loan Credit Agreement \| Tranche 3 \| Two Thousand Nineteen Term Loan
Debt Instrument [Line Items]
Loan and security agreement available upon revenue achievement	15,000,000.0
Revolving Loan Credit Agreement
Debt Instrument [Line Items]
Term loan, face amount		$ 10,000,000.0	$ 8,500,000
Loan and security agreement available upon revenue achievement	$ 10,000,000.0
Debt instrument floating interest rate percentage	1.80%
Borrowing limit	$ 10,000,000.0
Revolving Loan Credit Agreement \| Two Thousand Nineteen Term Loan
Debt Instrument [Line Items]
Debt instrument maturity date	Mar. 01, 2024