Goodwill and Other Identifiable Intangible Assets - Other Identifiable Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Nov. 25, 2012	May 27, 2012
Goodwill [Line Items]
Non-amortizing intangible assets, gross carrying amount	$ 1,017.8	$ 947.7
Amortizing intangible assets, gross carrying amount	369.7	313.8
Intangible assets, gross carrying amount	1,387.5	1,261.5
Non-amortizing intangible assets, accumulated amortization
Amortizing intangible assets, accumulated amortization	83.5	70.0
Intangible assets, accumulated amortization	$ 83.5	$ 70.0

Indefinite lived intangible assets accumulated amortization.

No definition available.

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- Definition

Intangible Assets Accumulated Amortization Excluding Goodwill

+ References

No definition available.

+ Details

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Namespace Prefix:	cag_
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Balance Type:	credit
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- Definition

Intangible assets gross excluding goodwill.

+ References

No definition available.

+ Details

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Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount of assets (excluding financial assets) that lack physical substance, excluding goodwill, having a projected indefinite period of benefit.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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