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Stockholders Equity - Additional Information (Detail) (USD $) | 1 Months Ended | 3 Months Ended | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jan. 31, 2015 | Mar. 31, 2015 | Mar. 31, 2014 | Nov. 30, 2010 | Dec. 31, 2014 | Aug. 31, 2009
Stockholders Equity Note [Line Items] |  |  |  |  |  |
Common stock, number of shares issued | 14,636,363 us-gaap_StockIssuedDuringPeriodSharesNewIssues |  |  |  |  |
Common stock, par value | $ 0.001 us-gaap_CommonStockParOrStatedValuePerShare |  |  |  |  |
Public offering, price per share | $ 5.50 us-gaap_SharePrice |  |  |  |  |
Estimated Net proceeds from public offering | $ 75,400,000 cers_EstimatedNetProceedsFromPublicOffering |  |  |  |  |
Underwriting discounts and other issuance costs | 5,100,000 us-gaap_PaymentsOfStockIssuanceCosts |  |  |  |  |
Gain (Loss) from revaluation of warrant liability |  | 6,300,000 cers_WarrantLiabilityRevaluationGainLoss | 9,000,000 cers_WarrantLiabilityRevaluationGainLoss |  |  |
Proceeds from common stock sold |  | 75,527,000 us-gaap_ProceedsFromIssuanceOfCommonStock | 31,000 us-gaap_ProceedsFromIssuanceOfCommonStock |  |  |
2009 Unit Offering |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |
Warrants to purchase an aggregate shares of common stock |  |  |  |  |  | 2,400,000 us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = cers_TwoThousandNineUnitOfferingMember
Warrant exercise price |  |  |  |  |  | $ 2.90 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cers_TwoThousandNineUnitOfferingMember
2010 Unit Offering |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |
Warrants to purchase an aggregate shares of common stock |  |  |  | 3,700,000 us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = cers_TwoThousandTenUnitOfferingMember |  |
Warrant exercise price |  |  |  | 3.20 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_ClassOfWarrantOrRightAxis = cers_TwoThousandTenUnitOfferingMember |  |
2010 Unit Offering | Warrant |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |
Warrants exercisable date |  |  |  | May 15, 2011 |  |
Exercisable period |  |  |  | 5 years |  |
Warrants exercised |  | 0 cers_WarrantsExercised / us-gaap_ClassOfWarrantOrRightAxis = cers_TwoThousandTenUnitOfferingMember / us-gaap_StatementEquityComponentsAxis = us-gaap_WarrantMember |  |  |  |
Sales Agreement | Cantor |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |
Common stock, number of shares issued |  | 0 us-gaap_StockIssuedDuringPeriodSharesNewIssues / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |  |  | 4,300,000 us-gaap_StockIssuedDuringPeriodSharesNewIssues / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |
Maximum common stock offering price |  | 70,000,000 cers_MaximumAmountAvailableUnderOffering / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |  |  |  |
Percentage of proceeds payable as compensation to underwriter |  | 2.00%cers_PercentageOfProceedsPayableAsCompensationToUnderwriter / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |  |  |  |
Proceeds from common stock sold |  | 18,600,000 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |  |  |  |
Common stock available for sale |  | $ 22,500,000 cers_CommonStockSharesAvailableForSaleValue / dei_LegalEntityAxis = cers_CantorMember / us-gaap_StatementClassOfStockAxis = cers_SalesAgreementMember |  |  |  |

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- Definition The non-cash net impact of the mark-to-market of the outstanding warrant based on the binomial model valuation. This element refers to the gain (loss). + References No definition available. + Details
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- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(4)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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