Segment Reporting (Details) $ in Millions		12 Months Ended
	Dec. 31, 2014 Segment	Aug. 31, 2015 USD ($) Segment Customer	Aug. 31, 2014 USD ($)	Aug. 31, 2013 USD ($)	Aug. 02, 2012
Segment Reporting [Abstract]
Number of reportable segments | Segment	3	3
Segment Reporting Information [Line Items]
Number of customers | Customer		0
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		$ 103,444	$ 76,392	$ 72,217
Adjusted Operating Income		6,157	4,866	4,828
Depreciation and amortization		1,742	1,316	1,283
Additions to property, plant and equipment		1,251	1,106	1,212
Asset impairment			(167)	(30)
Gain (Loss) on sale of business		0	0	20
Operating Income		4,668	$ 4,194	4,092
Alliance Boots [Member]
Segment Reporting Information [Line Items]
Equity interest in Alliance Boots	45.00%		45.00%		45.00%
Segment Reporting Information, Operating Income (Loss) [Abstract]
Acquisition-related amortization		(14)	$ (41)	(68)
Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		80,974	76,392	72,217
Adjusted Operating Income		5,098	4,866	4,828
Depreciation and amortization		1,217	1,316	1,283
Additions to property, plant and equipment		$ 951	1,106	1,212
Retail Pharmacy USA [Member] | Revenues [Member]
Segment Reporting Information [Line Items]
Number of customers | Customer		1
Concentration risk		12.30%
Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		$ 8,657	0	0
Adjusted Operating Income		616	0	0
Depreciation and amortization		393	0	0
Additions to property, plant and equipment		$ 249	0	0
Retail Pharmacy International [Member] | Revenues [Member]
Segment Reporting Information [Line Items]
Number of customers | Customer		1
Concentration risk		20.00%
Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		$ 13,813	0	0
Adjusted Operating Income		450	0	0
Depreciation and amortization		120	0	0
Additions to property, plant and equipment		51	0	0
Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Adjusted Operating Income		(7)	0	0
Depreciation and amortization		12	0	0
Additions to property, plant and equipment		0	0	0
Operating Segments [Member] | Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		80,974	76,392	72,217
Adjusted Operating Income		5,098	4,866	4,828
Operating Segments [Member] | Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		8,781	0	0
Adjusted Operating Income		616	0	0
Operating Segments [Member] | Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		15,327	0	0
Adjusted Operating Income		450	0	0
Intersegment Eliminations [Member] | Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		0	0	0
Intersegment Eliminations [Member] | Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		124	0	0
Intersegment Eliminations [Member] | Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		1,514	0	0
Intersegment Eliminations [Member] | Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		(1,638)	0	0
Reconciling Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Cost transformation		(542)
Acquisition-related amortization		(515)	(364)	(394)
LIFO provision		(285)	(132)	(239)
Asset impairment		(110)
Acquisition-related costs		(87)	(82)	(96)
Store closures and other optimization costs		(56)	(271)
Hurricane Sandy costs				(39)
DEA settlement costs				(28)
Distributor transition costs				(13)
Gain (Loss) on sale of business		(17)	9	20
Increase in fair market value of warrants		$ 123	$ 168	$ 53