PENSION AND POSTRETIREMENT BENEFITS - Narrative (Details) $ in Millions	3 Months Ended
Aug. 28, 2016 USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted average discount rate for service costs	4.14%
Weighted average discount rate for interest costs	3.15%
Employer contributions to pension and other postretirement plans	$ 3.0
Further contribution to pension and other postretirement plans	9.5
Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions to pension and other postretirement plans	4.5
Further contribution to pension and other postretirement plans	17.6
Change in Assumptions for Pension Plans \| Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pre-tax reduction in total pension benefit cost	$ 7.4

Defined Benefit Plan, Interest Cost, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate

No definition available.

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

- Definition

Defined Benefit Plan, Service Cost, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate

+ References

No definition available.

+ Details

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

- Definition

Defined Benefit Plans, Estimated Future Employer Contributions in Remainder of Fiscal Year

+ References

No definition available.

+ Details

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

- Definition

Amount of contributions made by the employer to defined benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(ii)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 35
-Paragraph 123
-Subparagraph B
-URI http://asc.fasb.org/extlink&oid=64937487&loc=d3e36068-114959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 63
-Subparagraph B
-URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12551-114930

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in the amount due to fund retirement benefits to employees, retired and disabled former employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

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

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ChangeInAccountingEstimateByTypeAxis=us-gaap_ChangeInAssumptionsForPensionPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: