Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	Other
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 07, 2011
Registrant Name	dei_EntityRegistrantName	JANUS ASPEN SERIES
Central Index Key	dei_EntityCentralIndexKey	0000906185
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Sep. 16, 2011
Document Effective Date	dei_DocumentEffectiveDate	Dec. 07, 2011
Prospectus Date	rr_ProspectusDate	Aug. 31, 2011
Moderate Allocation Portfolio
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	jas906185_SupplementTextBlock	Janus Aspen Series Moderate Allocation Portfolio Supplement dated September 16, 2011 to Currently Effective Prospectuses Effective December 7, 2011, the following change applies as noted.
Supplement Objective [Text Block]	jas906185_SupplementObjectiveTextBlock	The following replaces the corresponding information in its entirety under “Investment Objective” in the Portfolio Summary section of the Prospectus for Moderate Allocation Portfolio:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Moderate Allocation Portfolio seeks total return through growth of capital and income.

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The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

+ Details

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The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ Details

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The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements this will be the filing date. The format of the date is CCYY-MM-DD.

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- Definition

The type of document being provided (such as 10-K, 10-Q, N-1A, etc). The document type should be limited to the same value as the supporting SEC submission type. The acceptable values are as follows: S-1, S-3, S-4, S-11, F-1, F-3, F-4, F-9, F-10, 6-K, 8-K, 10, 10-K, 10-Q, 20-F, 40-F, N-1A, 485BPOS, NCSR, N-Q, and Other.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

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

-Publisher SEC

-Name Regulation 12B

-Number 240

-Section 12b

-Subsection 1

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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

-Publisher SEC

-Name Regulation 12B

-Number 240

-Section 12b

-Subsection 1

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Supplement Objective.

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Supplement.

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Investment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).

+ References

Reference 1: 1

-Publisher SEC

-Name Form

-Number N-1A

-Chapter A

-Section 2

-Subsection a

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The date of the prospectus.

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Reference 1: 1

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-Name Form

-Number N-1A

-Chapter A

-Section 1

-Paragraph 3

-Subsection a

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