Change in Accounting Policy (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
		Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2012
Consolidated Statements of Earnings [Abstract]
Equity earnings in Alliance Boots	[1]									$ 339	$ 618	$ 496
Operating Income										4,668	4,194	4,092
Earnings Before Income Tax Provision										5,311	3,557	4,047
Income tax provision										1,056	1,526	1,499
Net Earnings										4,279	2,031	2,548
Net Earnings Attributable to Walgreens Boots Alliance, Inc.		$ 26	$ 1,302	$ 2,042	$ 850	$ (221)	$ 714	$ 716	$ 723	$ 4,220	$ 1,932	$ 2,548
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)		$ 0.02	$ 1.19	$ 1.96	$ 0.90	$ (0.23)	$ 0.75	$ 0.75	$ 0.76	$ 4.05	$ 2.03	$ 2.69
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)		$ 0.02	$ 1.18	$ 1.93	$ 0.89	$ (0.23)	$ 0.74	$ 0.74	$ 0.75	$ 4.00	$ 2.00	$ 2.67
Consolidated Statements of Comprehensive Income [Abstract]
Net Earnings										$ 4,279	$ 2,031	$ 2,548
Share of other comprehensive income (loss) of Alliance Boots										113	(18)	(95)
Cumulative translation adjustments										(622)	215	(61)
Total Other Comprehensive Income										(356)	228	(160)
Total Comprehensive Income										3,923	2,259	2,388
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.										3,870	2,160	2,388
Non-Current Assets [Abstract]
Equity investment in Alliance Boots		$ 0				$ 7,336				0	7,336
Total Non-Current Assets		49,125				25,008				49,125	25,008
Total Assets		68,782				37,250				68,782	37,250
Non-Current Liabilities [Abstract]
Deferred income taxes		3,538				1,080				3,538	1,080
Total Non-Current Liabilities		20,925				7,738				20,925	7,738
Equity [Abstract]
Retained earnings		25,089				22,327				25,089	22,327
Accumulated other comprehensive income		(214)								(214)
Total Walgreens Boots Alliance Inc. Shareholders' Equity		30,861				20,513				30,861	20,513
Total Equity		31,300				20,617				31,300	20,617	19,558	$ 18,236
Total Liabilities and Equity		$ 68,782				37,250				68,782	37,250
Cash Flows from Operating Activities [Abstract]
Net earnings										4,279	2,031	2,548
Deferred income taxes										(32)	177	202
Equity earnings in Alliance Boots	[1]									$ (339)	(618)	(496)
Reduction in non-current assets and non-current liabilities											(20)
Increase in retained earnings, net of tax											98
Alliance Boots [Member]
Change in Accounting Estimate [Line Items]
Percentage of intial interest													45.00%
Consolidated Statements of Earnings [Abstract]
Equity earnings in Alliance Boots											617	496
Non-Current Assets [Abstract]
Equity investment in Alliance Boots						7,336					7,336
Cash Flows from Operating Activities [Abstract]
Equity earnings in Alliance Boots											(617)	(496)
As Reported [Member]
Consolidated Statements of Earnings [Abstract]
Operating Income											4,194	3,940
Earnings Before Income Tax Provision											3,557	3,895
Income tax provision											1,526	1,445
Net Earnings											2,031	2,450
Net Earnings Attributable to Walgreens Boots Alliance, Inc.											$ 1,932	$ 2,450
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)											$ 2.03	$ 2.59
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)											$ 2.00	$ 2.56
Consolidated Statements of Comprehensive Income [Abstract]
Net Earnings											$ 2,031	$ 2,450
Share of other comprehensive income (loss) of Alliance Boots											(41)	(59)
Cumulative translation adjustments											286	(103)
Total Other Comprehensive Income											276	(166)
Total Comprehensive Income											2,307	2,284
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.											2,208	2,284
Non-Current Assets [Abstract]
Total Non-Current Assets	[2]					24,920					24,920
Total Assets	[2]					37,162					37,162
Non-Current Liabilities [Abstract]
Deferred income taxes	[2]					1,048					1,048
Total Non-Current Liabilities	[2]					7,706					7,706
Equity [Abstract]
Retained earnings	[2]					22,229					22,229
Accumulated other comprehensive income	[2]					178					178
Total Walgreens Boots Alliance Inc. Shareholders' Equity	[2]					20,457					20,457
Total Equity	[2]					20,561					20,561
Total Liabilities and Equity	[2]					37,162					37,162
Cash Flows from Operating Activities [Abstract]
Net earnings											2,031	2,450
Deferred income taxes												148
As Reported [Member] | Alliance Boots [Member]
Consolidated Statements of Earnings [Abstract]
Equity earnings in Alliance Boots											617	344
Non-Current Assets [Abstract]
Equity investment in Alliance Boots	[2]					7,248					7,248
Cash Flows from Operating Activities [Abstract]
Equity earnings in Alliance Boots											(617)	(344)
Adjustments [Member]
Consolidated Statements of Earnings [Abstract]
Operating Income											0	152
Earnings Before Income Tax Provision											0	152
Income tax provision											0	54
Net Earnings											0	98
Net Earnings Attributable to Walgreens Boots Alliance, Inc.											$ 0	$ 98
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)											$ 0	$ 0.10
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)											$ 0	$ 0.11
Consolidated Statements of Comprehensive Income [Abstract]
Net Earnings											$ 0	$ 98
Share of other comprehensive income (loss) of Alliance Boots											23	(36)
Cumulative translation adjustments											(71)	42
Total Other Comprehensive Income											(48)	6
Total Comprehensive Income											(48)	104
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.											(48)	104
Non-Current Assets [Abstract]
Total Non-Current Assets						88					88
Total Assets						88					88
Non-Current Liabilities [Abstract]
Deferred income taxes						32					32
Total Non-Current Liabilities						32					32
Equity [Abstract]
Retained earnings						98					98
Accumulated other comprehensive income						(42)					(42)
Total Walgreens Boots Alliance Inc. Shareholders' Equity						56					56
Total Equity						56					56
Total Liabilities and Equity						88					88
Cash Flows from Operating Activities [Abstract]
Net earnings											0	98
Deferred income taxes												54
Adjustments [Member] | Alliance Boots [Member]
Consolidated Statements of Earnings [Abstract]
Equity earnings in Alliance Boots											0	152
Non-Current Assets [Abstract]
Equity investment in Alliance Boots						$ 88					88
Cash Flows from Operating Activities [Abstract]
Equity earnings in Alliance Boots											$ 0	$ (152)

[1] Earnings in foreign equity method investments are translated at their respective average exchange rates.

[2] Due to the adoption of Accounting Standards Update 2015-03, Interest - Imputation of Interest, all reported periods include debt issuance costs as a contra-liability, This impacted the August 31, 2014 Consolidated Balance Sheet by reducing non-current assets and non-current liabilities by $20 million.