The initial applicable margin percentage points added to the debt instrument.

No definition available.

Name:	unfi_DebtInstrumentInitialApplicableMargin
Namespace Prefix:	unfi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Real estate term backed loan

+ References

No definition available.

+ Details

Name:	unfi_Realestatetermbackedloan
Namespace Prefix:	unfi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, collateralized financings, and capital lease obligations.

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	unfi_DebtInstrumentVariableRateBaseAxis=unfi_DebtInstrumentVariableRateFederalFundsEffectiveRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	unfi_DebtInstrumentVariableRateBaseAxis=unfi_DebtInstrumentVariableRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	unfi_DebtInstrumentVariableRateBaseAxis=unfi_DebtInstrumentVariableRateNineMonthLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	unfi_DebtInstrumentVariableRateBaseAxis=unfi_DebtInstrumentVariableRateOneMonthLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SUBSEQUENT EVENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	0 Months Ended
	Nov. 01, 2014	May 31, 2012	Aug. 14, 2014
Term Loan
Subsequent Event [Line Items]
Initial borrowings under term loan agreement			$ 150.0
Repayments of Debt	2.5
Initial applicable margin			2.50%
Minimum \| Term Loan
Subsequent Event [Line Items]
Proceeds from Issuance of Debt	10.0
Maximum \| Term Loan
Subsequent Event [Line Items]
Proceeds from Issuance of Debt	50.0
Federal funds effective rate \| Term Loan
Subsequent Event [Line Items]
Reference rate	federal funds effective rate
Spread on reference rate (as a percent)	0.50%
One-month LIBOR \| Term Loan
Subsequent Event [Line Items]
Reference rate	one-month LIBOR
Spread on reference rate (as a percent)	1.00%
Nine month LIBOR \| Term Loan
Subsequent Event [Line Items]
Initial applicable margin			1.50%
LIBOR \| Term Loan
Subsequent Event [Line Items]
Reference rate	for one, two, three or six months or, if approved by all affected lenders, nine months
Term Loan
Subsequent Event [Line Items]
Real estate term backed loan		$ 200.0