Change in Accounting Policy (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended				12 Months Ended
	Feb. 28, 2015		Feb. 28, 2014		Feb. 28, 2015		Feb. 28, 2014		Aug. 31, 2014	Nov. 30, 2014	Nov. 30, 2013	Aug. 31, 2013	Aug. 31, 2012
Consolidated Condensed Statements of Earnings [Abstract]
Equity earnings in Alliance Boots	$ 109	[1]	$ 136	[1]	$ 323	[1]	$ 330	[1]
Operating Income	1,377		1,217		2,431		2,184
Earnings Before Income Tax Provision	2,443		1,121		3,641		2,272
Income tax provision	391		391		712		810
Net Earnings (loss)	2,060		730		2,937		1,462
Net Earnings Attributable to Walgreens Boots Alliance, Inc.	2,042		716		2,892		1,439
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)	$ 1.96		$ 0.75		$ 2.91		$ 1.51
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)	$ 1.93		$ 0.74		$ 2.88		$ 1.49
Consolidated Condensed Statements of Comprehensive Income [Abstract]
Net earnings	2,060		730		2,937		1,462
Share of other comprehensive income (loss) of Alliance Boots	92		(19)		113		(56)
Cumulative translation adjustments	(301)		116		(490)		281
Total Other Comprehensive Income	(127)		46		(209)		266
Total Comprehensive Income (loss)	1,933		776		2,728		1,728
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.	1,920		762		2,688		1,705
Non-Current Assets [Abstract]
Equity investment in Alliance Boots	0				0				7,336
Total Non-Current Assets	50,642				50,642				25,028
Total Assets	71,357				71,357				37,270
Non-Current Liabilities [Abstract]
Deferred income taxes	3,689				3,689				1,080
Total Non-Current Liabilities	23,641				23,641				7,758
Equity [Abstract]
Retained earnings	24,526				24,526				22,327
Accumulated other comprehensive income	(68)		174		(68)		174		136	54	128	(92)
Total Walgreens Boots Alliance Inc. Shareholders' Equity	30,814				30,814				20,513
Total Equity	31,026				31,026				20,617
Total Liabilities and Equity	71,357				71,357				37,270
Cash Flows from Operating Activities [Abstract]
Net earnings	2,060		730		2,937		1,462
Deferred income taxes					181		29
Equity earnings in Alliance Boots	(109)	[1]	(136)	[1]	(323)	[1]	(330)	[1]
Increase in retained earnings, net of tax									98
Alliance Boots [Member]
Non-Current Assets [Abstract]
Equity investment in Alliance Boots									7,336
Cash Flows from Operating Activities [Abstract]
Percentage of initial interest													45.00%
As Reported [Member]
Consolidated Condensed Statements of Earnings [Abstract]
Equity earnings in Alliance Boots			194				345
Operating Income			1,275				2,199
Earnings Before Income Tax Provision			1,179				2,287
Income tax provision			411				815
Net Earnings (loss)			768				1,472
Net Earnings Attributable to Walgreens Boots Alliance, Inc.			754				1,449
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)			$ 0.79				$ 1.52
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)			$ 0.78				$ 1.51
Consolidated Condensed Statements of Comprehensive Income [Abstract]
Net earnings			768				1,472
Share of other comprehensive income (loss) of Alliance Boots			(36)				(70)
Cumulative translation adjustments			191				253
Total Other Comprehensive Income			104				224
Total Comprehensive Income (loss)			872				1,696
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.			858				1,673
Non-Current Assets [Abstract]
Equity investment in Alliance Boots									7,248
Total Non-Current Assets									24,940
Total Assets									37,182
Non-Current Liabilities [Abstract]
Deferred income taxes									1,048
Total Non-Current Liabilities									7,726
Equity [Abstract]
Retained earnings									22,229
Accumulated other comprehensive income									178
Total Walgreens Boots Alliance Inc. Shareholders' Equity									20,457
Total Equity									20,561
Total Liabilities and Equity									37,182
Cash Flows from Operating Activities [Abstract]
Net earnings			768				1,472
Deferred income taxes							34
Equity earnings in Alliance Boots			(194)				(345)
Adjustments [Member]
Consolidated Condensed Statements of Earnings [Abstract]
Equity earnings in Alliance Boots			(58)				(15)
Operating Income			(58)				(15)
Earnings Before Income Tax Provision			(58)				(15)
Income tax provision			(20)				(5)
Net Earnings (loss)			(38)				(10)
Net Earnings Attributable to Walgreens Boots Alliance, Inc.			(38)				(10)
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - basic (in dollars per share)			$ (0.04)				$ (0.01)
Net earnings per common share attributable to Walgreens Boots Alliance, Inc. - diluted (in dollars per share)			$ (0.04)				$ (0.02)
Consolidated Condensed Statements of Comprehensive Income [Abstract]
Net earnings			(38)				(10)
Share of other comprehensive income (loss) of Alliance Boots			17				14
Cumulative translation adjustments			(75)				28
Total Other Comprehensive Income			(58)				42
Total Comprehensive Income (loss)			(96)				32
Comprehensive Income Attributable to Walgreens Boots Alliance, Inc.			(96)				32
Non-Current Assets [Abstract]
Equity investment in Alliance Boots									88
Total Non-Current Assets									88
Total Assets									88
Non-Current Liabilities [Abstract]
Deferred income taxes									32
Total Non-Current Liabilities									32
Equity [Abstract]
Retained earnings									98
Accumulated other comprehensive income									(42)
Total Walgreens Boots Alliance Inc. Shareholders' Equity									56
Total Equity									56
Total Liabilities and Equity									88
Cash Flows from Operating Activities [Abstract]
Net earnings			(38)				(10)
Deferred income taxes							(5)
Equity earnings in Alliance Boots			$ 58				$ 15

[1] Alliance Boots became a consolidated subsidiary and ceased being accounted for under the equity method upon completion of the Second Step Transaction on December 31, 2014. Earnings for the quarter and six month periods ended February 28, 2015 reflect incremental acquisition-related amortization expense of $4 million ($3 million net of tax) and $14 million ($8 million net of tax), respectively. Incremental acquisition-related amortization for the three and six month periods ended February 28, 2014 were $10 million ($8 million net of tax) and $20 million ($16 million net of tax), respectively. Earnings in foreign equity method investments and joint ventures are translated at the average exchange rates of $1.56 and $1.58 to one British Pound Sterling for the quarter and six month periods ended February 28, 2015, respectively. Prior year's earnings in foreign equity method investments and joint ventures were translated at the average exchange rate of $1.64 and $1.62 to one British Pound Sterling for the quarter and six month periods ended February 28, 2014, respectively.