Represents the amount of interest, prepayment and final payment fees paid by the entity.

No definition available.

Name:	cldx_DebtInstrumentInterestAndPrepaymentFees
Namespace Prefix:	cldx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of principal repaid by the entity.

+ References

No definition available.

+ Details

Name:	cldx_RepaymentOfLongTermDebtPrincipalAmount
Namespace Prefix:	cldx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

Aggregate amount of interest paid or due on all long-term debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.8)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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

- Details

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

- Details

Name:	cldx_DebtInstrumentLenderAxis=cldx_MidCapFinancialLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cldx_DebtInstrumentLenderAxis=cldx_GeneralElectricCapitalCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

TERM LOAN (Details) - Term Loan - USD ($) $ in Millions	1 Months Ended			12 Months Ended
TERM LOAN (Details) - Term Loan - USD ($) $ in Millions	May. 31, 2013	Mar. 31, 2011	Dec. 31, 2010	Dec. 31, 2013
Term Loan
Repayment of principal amount	$ 8.8
Amount of interest, prepayment and final payment fees	$ 0.7
Interest expense on the term loan				$ 0.8
MidCap
Term Loan
Amount borrowed			$ 10.0
GECC
Term Loan
Amount borrowed		$ 5.0