Supplementary Financial Information, Summary of Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
		Aug. 31, 2016		May 31, 2016		Feb. 29, 2016		Nov. 30, 2015		Aug. 31, 2015		May 31, 2015		Feb. 28, 2015		Nov. 30, 2014		Aug. 31, 2016		Aug. 31, 2015		Aug. 31, 2014
Supplementary Financial Information [Abstract]
Sales		$ 28,636	[1]	$ 29,498	[1]	$ 30,184	[1]	$ 29,033	[1]	$ 28,522	[1]	$ 28,795	[1]	$ 26,573	[1]	$ 19,554	[1]	$ 117,351	[1]	$ 103,444	[1]	$ 76,392
Gross Profit		7,155	[1]	7,433	[1]	7,867	[1]	7,419	[1]	7,195	[1]	7,420	[1]	6,842	[1]	5,296	[1]	29,874	[1]	26,753	[1]	21,569
Net Earnings attributable to Walgreens Boots Alliance, Inc.		$ 1,030	[1]	$ 1,103	[1]	$ 930	[1]	$ 1,110	[1]	$ 26	[1]	$ 1,302	[1]	$ 2,042	[1]	$ 850	[1]	$ 4,173	[1]	$ 4,220	[1]	$ 1,932
Net earnings per common share [Abstract]
Basic (in dollars per share)	[1]	$ 0.95		$ 1.02		$ 0.86		$ 1.02		$ 0.02		$ 1.19		$ 1.96		$ 0.90		$ 3.85		$ 4.05
Diluted (in dollars per share)	[1]	0.95		1.01		0.85		1.01		0.02		1.18		1.93		0.89		3.82		4.00
Cash Dividends Declared Per Common Share (in dollars per share)		$ 0.3750	[1]	$ 0.3600	[1]	$ 0.3600	[1]	$ 0.3600	[1]	$ 0.3600	[1]	$ 0.3375	[1]	$ 0.3375	[1]	$ 0.3375	[1]	$ 1.4550	[1]	$ 1.3725	[1]	$ 1.28

[1] To improve comparability, certain classification changes have been made to fiscal 2016 for the quarterly periods ended November 30, 2015, February 29, 2016, and May 31, 2016 and to fiscal 2015 for the quarterly periods ended February 29, 2015, May 31, 2015, and August 31, 2015 to Sales, Cost of sales and Selling, general and administrative expenses. This change has no impact on Operating Income.