QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Aug. 03, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 28, 2018	Apr. 28, 2018	Jan. 27, 2018	Oct. 28, 2017	Aug. 03, 2019	Jul. 28, 2018	Jul. 29, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net sales	$ 6,407,086	$ 5,962,620	$ 6,149,206	$ 2,868,156	$ 2,592,248	$ 2,648,879	$ 2,528,011	$ 2,457,545	$ 21,387,068	$ 10,226,683	$ 9,274,471
Gross profit	822,346	788,550	761,783	412,331	375,942	408,087	371,522	367,216	2,785,010	1,522,767	1,428,921
Net (loss) income from continuing operations	1,207	32,774	(363,303)	(21,361)	32,788	51,891	50,486	30,505	(350,683)	165,670	130,155
Income from discontinued operations, net of tax	17,953	24,370	21,407	2,070	0	0	0	0	65,800	0	0
Net (loss) income including noncontrolling interests	19,160	57,144	(341,896)	(19,291)	32,788	51,891	50,486	30,505	(284,883)	165,670	130,155
Net (loss) income attributable to United Natural Foods, Inc.	$ 18,937	$ 57,092	$ (341,725)	$ (19,294)	$ 32,788	$ 51,891	$ 50,486	$ 30,505	$ (284,990)	$ 165,670	$ 130,155
Basic (loss) earnings per share:
Continuing operations (in dollars per share)	$ 0.02	$ 0.64	$ (7.15)	$ (0.42)	$ 0.65	$ 1.03	$ 1.00	$ 0.60	$ (6.84)	$ 3.28	$ 2.57
Basic (loss) income per share (in dollars per share)	0.36	1.12	(6.72)	(0.38)	0.65	1.03	1.00	0.60	(5.56)	3.28	2.57
Diluted (loss) earnings per share:
Continuing operations (in dollars per share)	0.02	0.64	(7.15)	(0.42)	0.64	1.02	0.99	0.60	(6.84)	3.26	2.56
Diluted (loss) income per share (in dollars per share)	$ 0.36	$ 1.12	$ (6.72)	$ (0.38)	$ 0.64	$ 1.02	$ 0.99	$ 0.60	$ (5.56)	$ 3.26	$ 2.56
Retained Earnings
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net (loss) income attributable to United Natural Foods, Inc.									$ (284,990)