Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2011
Registrant Name	dei_EntityRegistrantName	INVESTMENT CO OF AMERICA
Central Index Key	dei_EntityCentralIndexKey	0000051931
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Feb. 29, 2012
Document Effective Date	dei_DocumentEffectiveDate	Mar. 01, 2012
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AIVSX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class B
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AICBX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AICCX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AICFX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class F-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	ICAFX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class 529-A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CICAX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class 529-B
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CICBX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class 529-C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CICCX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class 529-E
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CICEX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class 529-F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CICFX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICAX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICBX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-3
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICCX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-4
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICEX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-5
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICFX
INVESTMENT CO OF AMERICA (Prospectus Summary) \| INVESTMENT CO OF AMERICA \| Class R-6
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RICGX

If the value is true, then the document as an amendment to previously-filed/accepted document.

No definition available.

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Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- 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.

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	us-types:SECReportItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	us-types:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation 12B

-Number 240

-Section 12b

-Subsection 1

+ Details

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Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:	dei_TradingSymbol
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	rr_RiskReturnAbstract
Namespace Prefix:	rr_
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