Amount of contingent consideration paid to acquire the entity.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Represents the period over which branded product company acquisition requires ongoing contingent consideration payments in the form of earn-outs.

+ References

No definition available.

+ Details

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Namespace Prefix:	unfi_
Data Type:	xbrli:integerItemType
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Period Type:	duration

- Definition

Represents the ongoing contingent consideration payments in the form of royalties as a percentage of the net sales.

+ References

No definition available.

+ Details

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Namespace Prefix:	unfi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the potential earn-outs as per the assets purchase agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the number of trailing months of tiers of net sales used for calculation of earn-outs.

+ References

No definition available.

+ Details

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- Definition

Represents the number of businesses acquired by the entity which requires ongoing contingent consideration payments in the form of royalties.

+ References

No definition available.

+ Details

Name:	unfi_NumberOfBusinessesAcquiredWhichRequiresPaymentOfRoyalty
Namespace Prefix:	unfi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate amount assigned to a major class of finite-lived intangible assets acquired either individually or as part of a group of assets (in either an asset acquisition or business combination). A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 44

-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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16265-109275

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The calculated weighted-average amortization period of a major class of finite-lived intangible assets acquired during the current period either individually or as part of a group of assets (in either an asset acquisition or business combination). A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 44

-Subparagraph a(3)

-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 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16265-109275

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash paid to acquire the entity.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-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 141R

-Paragraph 68

-Subparagraph f(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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=6909870&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph g

-Clause 3

-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 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6911361&loc=d3e6927-128479

+ Details

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- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to intangibles acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph a(3)

-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 141R

-Paragraph 55

-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 805

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6909870&loc=d3e1500-128463

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

+ Details

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ACQUISITIONS (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended	9 Months Ended			6 Months Ended
	Apr. 28, 2012 Other M Y	Apr. 30, 2011 Other	Aug. 01, 2009 Other entity	Apr. 28, 2012 Other Minimum	Apr. 28, 2012 Other Maximum	Apr. 28, 2012 Whole Foods Distribution Wholesale	Jan. 28, 2012 Specialty food distribution Y	Apr. 28, 2012 Specialty food distribution
Acquisitions
Incremental annual revenues						$ 25.4
Cash consideration paid								3.0
Potential earn-outs							1.95
Identifiable intangible assets							0.8
Estimated useful life							9.7
Increase to intangible assets in recognition of ongoing contingent consideration payments	0.2
Ongoing contingent consideration payments in the form of royalties as a percentage of net sales				2.00%	4.00%
Number of branded product companies acquired for which ongoing contingent consideration payments in the form of royalties are recognized (in entities)			2
Number of branded product companies included in other segment (in entities)			3
Period over which contingent consideration payments are required in the form of earn-outs (in years)	5
Number of trailing months	12
Potential earn-outs	0.2
Contingent consideration paid		$ 0.1