Class of warrant or right expiration date.

No definition available.

Name:	ceru_ClassOfWarrantOrRightExpirationDate
Namespace Prefix:	ceru_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Class of warrant or right expiration period.

+ References

No definition available.

+ Details

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

- Definition

Class of warrant or right number of securities called by warrants or rights exercisable.

+ References

No definition available.

+ Details

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Namespace Prefix:	ceru_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt instrument accrued interest.

+ References

No definition available.

+ Details

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Namespace Prefix:	ceru_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ 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)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Subparagraph 2

-Article 4

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense (income) related to adjustment to fair value of warrant liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 25

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

+ Details

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

- Definition

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsExpectedTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsExpectedVolatilityRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsRiskFreeInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of interest payable on debt, including, but not limited to, trade payables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.15(5))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.15(a))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Subparagraph a

-Article 7

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Subparagraph 5

-Article 9

+ Details

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

- Definition

Increase for accrued, but unpaid interest on the credit facility for the period.

+ 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.(f))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

+ 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))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Article 4

+ Details

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- Details

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Loan Agreements - Additional Information (Detail) (USD $)	3 Months Ended					12 Months Ended			1 Months Ended					6 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2008	Aug. 31, 2008	Aug. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Aug. 31, 2012	Aug. 31, 2013	Apr. 30, 2014
Debt Instrument [Line Items]
Proceeds from loans payable								$ 10,000,000us-gaap_ProceedsFromNotesPayable
Debt instrument stated interest rate	7.00%														7.00%
Fair value of outstanding warrants		928,000us-gaap_WarrantsAndRightsOutstanding					928,000us-gaap_WarrantsAndRightsOutstanding
Fair value adjustment of warrant liability	(504,000)us-gaap_FairValueAdjustmentOfWarrants	42,000us-gaap_FairValueAdjustmentOfWarrants	7,000us-gaap_FairValueAdjustmentOfWarrants	(20,000)us-gaap_FairValueAdjustmentOfWarrants	(231,000)us-gaap_FairValueAdjustmentOfWarrants	(504,000)us-gaap_FairValueAdjustmentOfWarrants	(202,000)us-gaap_FairValueAdjustmentOfWarrants	(39,000)us-gaap_FairValueAdjustmentOfWarrants
Accrued interest		234,000ceru_DebtInstrumentAccruedInterest				574,000ceru_DebtInstrumentAccruedInterest	234,000ceru_DebtInstrumentAccruedInterest
Noncurrent accrued interest		391,000					391,000
Loan and Security Agreement with Bank [Member]
Debt Instrument [Line Items]
Loan and security agreement, maximum borrowing capacity										1,500,000
Proceeds from loans payable									695,000
Loan and security agreement, borrowings repayment period									48 months
Debt instrument stated interest rate									8.75%
Loan and Security Agreement with Bank [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Conversion of preferred warrants to common warrants.																1,695
Loan and Security Agreement with Bank [Member] \| Series B Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Conversion of preferred warrants to common warrants.										15,000
Exercise price of warrant										$ 2.00
Warrant expiration period										10 years
Fair value of outstanding warrants										25,000
Expected volatility										79.00%
Contractual life										10 years
Risk-free interest rate										3.89%
Expected dividends										0.00%
Loan and Security Agreement with Lighthouse Capital Partners VI, L.P. [Member]
Debt Instrument [Line Items]
Loan and security agreement, maximum borrowing capacity													10,000,000
Proceeds from loans payable											5,000,000	5,000,000		10,000,000
Loan and security agreement, borrowings repayment period													36 months
Debt instrument stated interest rate													8.25%
Loan and security agreement, borrowings repayment start date						Dec. 01, 2012
Line of credit facility, additional interest payment						600,000
Loan and Security Agreement with Lighthouse Capital Partners VI, L.P. [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Conversion of preferred warrants to common warrants.																66,436
Loan and Security Agreement with Lighthouse Capital Partners VI, L.P. [Member] \| Series D Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Conversion of preferred warrants to common warrants.													66,436
Exercise price of warrant													$ 12.04
Warrant expiration period													10 years
Fair value of outstanding warrants											$ 178,000	$ 182,000	$ 284,000	$ 178,000
Expected volatility											80.00%	80.00%	80.00%
Contractual life											9 years 3 months 15 days	9 years 8 months 9 days	10 years
Risk-free interest rate											1.68%	2.17%	1.98%
Warrant exercisable for preferred stock, shares		66,436				66,436	66,436						29,067
Warrant expiration date						2021-12