Reduction in net expense related to benefit retirement plan.

No definition available.

Name:	cag_DefinedBenefitPlanReductionInNetExpense
Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value investments ability to impose customary redemption gates.

+ References

No definition available.

+ Details

Name:	cag_FairValueInvestmentsAbilityToImposeCustomaryRedemptionGates
Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value investments impose customary redemption gates.

+ References

No definition available.

+ Details

Name:	cag_FairValueInvestmentsImposeCustomaryRedemptionGates
Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Green zone multiemployer plan funded percentage.

+ References

No definition available.

+ Details

Name:	cag_GreenZoneMultiemployerPlanFundedPercentage
Namespace Prefix:	cag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The expected incurrence of certain withdrawal costs related to multiemployer plans.

+ References

No definition available.

+ Details

Name:	cag_MultiemployerPlansExpectedWithdrawalCosts
Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cag_PensionAndPostretirementBenefitsAdditionalTextualAbstract
Namespace Prefix:	cag_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	cag_PensionAndPostretirementBenefitsTextualAbstract
Namespace Prefix:	cag_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage providing more than plans total contribution.

+ References

No definition available.

+ Details

Name:	cag_PercentageProvidingMoreThanPlansContribution
Namespace Prefix:	cag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Red zone multiemployer plans funded percentage.

+ References

No definition available.

+ Details

Name:	cag_RedZoneMultiemployerPlansFundedPercentage
Namespace Prefix:	cag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Unfunded commitment for additional investment.

+ References

No definition available.

+ Details

Name:	cag_UnfundedCommitmentForAdditionalInvestment
Namespace Prefix:	cag_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Yellow zone multiemployer plans funded percentage.

+ References

No definition available.

+ Details

Name:	cag_YellowZoneMultiemployerPlansFundedPercentage
Namespace Prefix:	cag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503844

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph e

-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

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

- Definition

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 158

-Paragraph 7

-Subparagraph c

-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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph i

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (j)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

+ Details

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

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph j

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

+ Details

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

- Definition

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-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

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

PENSION AND POSTRETIREMENT BENEFITS (Narrative) (Details) (USD $)	12 Months Ended
	May 26, 2013	May 27, 2012	May 29, 2011	Sep. 08, 2011
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Defined contribution plan, expected withdrawal costs			$ 14,200,000
Pension and Postretirement Benefits (Textual) [Abstract]
Discount rate			4.90%	4.30%
Calculated gains as a result of the remeasurement recognized as a credit to other comprehensive loss		27,600,000
Reduction in net expense related to benefit retirement plan		5,200,000
Expenses related to the defined contribution plans	30,700,000	24,200,000	21,200,000
Maximum
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Red zone multiemployer plans funded percentage	65.00%
Yellow zone multiemployer plans funded percentage	80.00%
Minimum
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Green zone multiemployer plan funded percentage	80.00%
Percentage of plan's total contribution under Forms 5500	5.00%
Level 3
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Fair value investments ability to impose customary redemption gates	506,800,000
Fair value investments impose customary redemption gates	3,100,000
Pension Benefits
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Accumulated benefit obligation	3,700,000,000	3,200,000,000
Anticipated contributions	19,100,000
Pension and Postretirement Benefits (Textual) [Abstract]
Discount rate	4.05%	4.50%
Calculated gains as a result of the remeasurement recognized as a credit to other comprehensive loss	(218,200,000)	(332,000,000)
Other Benefits
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Anticipated contributions	26,000,000
Pension and Postretirement Benefits (Textual) [Abstract]
Discount rate	3.35%	3.90%
Calculated gains as a result of the remeasurement recognized as a credit to other comprehensive loss	(66,900,000)	(80,500,000)
Private equity
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Unfunded commitment for additional investment	48,000,000
Private energy funds
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Unfunded commitment for additional investment	17,200,000
Real estate funds
Pension and Postretirement Benefits (Additional Textual) [Abstract]
Unfunded commitment for additional investment	$ 4,500,000