NOTES PAYABLE (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 28, 2012 quarter	May 31, 2012
Notes payable
Letter of credit commitments	$ 24.0
U.S. Borrowers
Notes payable
Maximum borrowing base	450.0
UNFI Canada
Notes payable
Maximum borrowing base	50.0
Amended and restated revolving credit facility
Notes payable
Maximum borrowing base		500.0
Additional increase in borrowing base	100
Borrowing base, based on eligible accounts receivable and inventory levels	483.7
Amount outstanding	115.0
Letter of credit commitments	24.0
Reserves	2.9
Remaining availability of credit facility	341.8
Minimum fixed charge coverage ratio, numerator	1
Minimum fixed charge coverage ratio, denominator	1.0
Number of quarters used to calculate fixed charge coverage ratio	4
Maximum aggregate availability of the aggregate borrowing base	$ 35.0
Percentage of maximum aggregate availability of the aggregate borrowing base (as a percent)	10.00%
Amended and restated revolving credit facility | Maximum
Notes payable
Term (in days)	180
Amended and restated revolving credit facility | Minimum
Notes payable
Term (in days)	30
Amended and restated revolving credit facility | UNFI Canada | Maximum
Notes payable
Annual commitment fee, percentage (as a percent)	0.30%
Average daily balance of amounts actually used for annual commitments fee, percentage (as a percent)	40.00%
Amended and restated revolving credit facility | UNFI Canada | Minimum
Notes payable
Annual commitment fee, percentage (as a percent)	0.25%
Average daily balance of amounts actually used for annual commitments fee, percentage (as a percent)	40.00%
Amended and restated revolving credit facility | Federal funds effective rate | U.S. Borrowers
Notes payable
Reference rate	federal funds effective rate
Spread on reference rate (as a percent)	0.50%
Amended and restated revolving credit facility | One-month LIBOR | U.S. Borrowers
Notes payable
Reference rate	one-month LIBOR
Spread on reference rate (as a percent)	1.00%
Initial applicable margin	0.50%
Amended and restated revolving credit facility | LIBOR | U.S. Borrowers
Notes payable
Reference rate	London Interbank Offered Rate ("LIBOR") for one, two, three or six months
Amended and restated revolving credit facility | Nine month LIBOR | U.S. Borrowers
Notes payable
Reference rate	nine months LIBOR
Initial applicable margin	1.50%
Amended and restated revolving credit facility | Reuters Canadian Deposit Offering Rate | UNFI Canada
Notes payable
Reference rate	30-day Reuters Canadian Deposit Offering Rate
Spread on reference rate (as a percent)	0.50%
Amended and restated revolving credit facility | Prime rate of Bank of America N.A.'s Canada branch | UNFI Canada
Notes payable
Reference rate	Bankers' acceptance equivalent rate for a one month interest period
Spread on reference rate (as a percent)	1.00%
Initial applicable margin	0.50%
Amended and restated revolving credit facility | Annual rates applicable to Canadian Dollar bankers' acceptances | UNFI Canada
Notes payable
Reference rate	annual rates applicable to CanadianDollar bankers' acceptances
Spread on reference rate (as a percent)	0.05%
Initial applicable margin	1.50%