Segment Reporting (Details) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 29, 2016 USD ($)	Feb. 28, 2015 USD ($)	Feb. 29, 2016 USD ($) Segment	Feb. 28, 2015 USD ($)	Dec. 31, 2014
Segment Reporting [Abstract]
Number of reportable segments | Segment			3
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	$ 30,184	$ 26,573	$ 59,217	$ 46,127
Adjusted Operating Income	2,120	1,840	3,839	2,958
Acquisition-related amortization	(101)	(217)	(182)	(306)
Cost transformation	(28)		(118)
LIFO provision	(68)	(55)	(114)	(107)
Store closures and other optimization costs		(16)		(44)
Acquisition-related costs	(33)	(59)	(67)	(83)
(Decrease) increase in fair market value of warrants		(6)		123
Asset impairment	(30)	(110)	(30)	(110)
Operating Income	$ 1,860	1,377	$ 3,328	2,431
Alliance Boots [Member]
Segment Reporting Information [Line Items]
Equity interest in Alliance Boots	45.00%		45.00%		45.00%
Walgreens Boots Alliance [Member]
Segment Reporting Information [Line Items]
Ownership percentage of WBA					55.00%
Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	$ 21,500	21,048	$ 41,870	40,602
Adjusted Operating Income	1,632	1,598	2,875	2,716
Acquisition-related amortization	0
Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	3,689	2,047	7,220	2,047
Adjusted Operating Income	335	125	650	125
Acquisition-related amortization	0
Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	5,627	3,865	11,423	3,865
Adjusted Operating Income	155	121	321	121
Acquisition-related amortization	0
Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	(632)	(387)	1,296	(387)
Adjusted Operating Income	(2)	(4)	(7)	(4)
Acquisition-related amortization	0
Reportable Segments [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	30,184	26,573	59,217	46,127
Adjusted Operating Income	2,120	1,840	3,839	2,958
Reportable Segments [Member] | Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	21,500	21,048	41,870	40,602
Adjusted Operating Income	1,632	1,598	2,875	2,716
Reportable Segments [Member] | Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	3,627	2,017	7,084	2,017
Adjusted Operating Income	335	125	650	125
Reportable Segments [Member] | Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	5,057	3,508	10,261	3,508
Adjusted Operating Income	155	121	321	121
Reportable Segments [Member] | Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	0	0	0	0
Intersegment Eliminations [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	0	0	0	0
Intersegment Eliminations [Member] | Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	0	0	0	0
Intersegment Eliminations [Member] | Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	62	30	134	30
Intersegment Eliminations [Member] | Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	570	357	1,162	357
Intersegment Eliminations [Member] | Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	$ (632)	$ (387)	$ 1,296	$ (387)