XML 98 R86.htm IDEA: XBRL DOCUMENT
v3.19.1

BENEFIT PLANS - Fair Value of Assets of Company's Benefit Plans Held in Master Trust (Details) $ in Thousands | Oct. 22, 2018 USD ($)
--- | ---
Changes in Plan Assets |
Total plan assets at fair value | $ 2,316,606
Assets Measured at NAV | 322,562
Common stock |
Changes in Plan Assets |
Total plan assets at fair value | 299,234
Assets Measured at NAV | 0
Common collective trusts |
Changes in Plan Assets |
Total plan assets at fair value | 818,052
Assets Measured at NAV | 78,230
Corporate bonds |
Changes in Plan Assets |
Total plan assets at fair value | 368,145
Assets Measured at NAV | 0
Government securities |
Changes in Plan Assets |
Total plan assets at fair value | 206,309
Assets Measured at NAV | 0
Mutual funds |
Changes in Plan Assets |
Total plan assets at fair value | 310,469
Assets Measured at NAV | 0
Mortgage-backed securities |
Changes in Plan Assets |
Total plan assets at fair value | 14,920
Assets Measured at NAV | 0
Other |
Changes in Plan Assets |
Total plan assets at fair value | 55,145
Assets Measured at NAV | 0
Private equity and real estate partnerships |
Changes in Plan Assets |
Total plan assets at fair value | 244,332
Assets Measured at NAV | 244,332
Level 1 |
Changes in Plan Assets |
Total plan assets at fair value | 404,103
Level 1 | Common stock |
Changes in Plan Assets |
Total plan assets at fair value | 299,234
Level 1 | Common collective trusts |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 1 | Corporate bonds |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 1 | Government securities |
Changes in Plan Assets |
Total plan assets at fair value | 51,030
Level 1 | Mutual funds |
Changes in Plan Assets |
Total plan assets at fair value | 887
Level 1 | Mortgage-backed securities |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 1 | Other |
Changes in Plan Assets |
Total plan assets at fair value | 52,952
Level 1 | Private equity and real estate partnerships |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 2 |
Changes in Plan Assets |
Total plan assets at fair value | 1,589,941
Level 2 | Common stock |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 2 | Common collective trusts |
Changes in Plan Assets |
Total plan assets at fair value | 739,822
Level 2 | Corporate bonds |
Changes in Plan Assets |
Total plan assets at fair value | 368,145
Level 2 | Government securities |
Changes in Plan Assets |
Total plan assets at fair value | 155,279
Level 2 | Mutual funds |
Changes in Plan Assets |
Total plan assets at fair value | 309,582
Level 2 | Mortgage-backed securities |
Changes in Plan Assets |
Total plan assets at fair value | 14,920
Level 2 | Other |
Changes in Plan Assets |
Total plan assets at fair value | 2,193
Level 2 | Private equity and real estate partnerships |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Common stock |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Common collective trusts |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Corporate bonds |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Government securities |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Mutual funds |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Mortgage-backed securities |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Other |
Changes in Plan Assets |
Total plan assets at fair value | 0
Level 3 | Private equity and real estate partnerships |
Changes in Plan Assets |
Total plan assets at fair value | $ 0

X
- Definition Fair value of investment in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes measurement of net asset value as estimate of fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258 + Details
Name: | us-gaap_AlternativeInvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + 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 (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=unfi_DefinedBenefitPlanEquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=unfi_DefinedBenefitPlanCommonCollectiveTrustMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_MutualFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_OtherAggregatedInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=unfi_PrivateEquityFundsAndRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |