Short-Term Borrowings and Long-Term Debt (Details) - Long-term Debt, Type [Domain] £ in Millions, $ in Millions	3 Months Ended	9 Months Ended
	May. 31, 2015 USD ($) $ / €	May. 31, 2015 USD ($) $ / €	May. 31, 2014 USD ($)	May. 31, 2015 GBP (£) $ / €	Dec. 31, 2014	Aug. 31, 2014 USD ($)
Long-Term Debt [Abstract]
Other short-term borrowings	$ 1,192	$ 1,192				$ 774
Spot rate					1.56
Maximum aggregate outstanding amount of indebtedness	$ 2,000	$ 2,000
Percentage of principal amount of fixed rate notes can be redeemed (in hundredths)	100.00%	100.00%
Alliance Boots [Member]
Long-Term Debt [Abstract]
Repayment of debt		$ 9,000
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Balance outstanding at fiscal year-end	$ 0	0	$ 0
Average daily short-term borrowings		$ 110	$ 5
Weighted-average interest rate (in hundredths)	0.52%	0.52%	0.23%	0.52%
United Kingdom, Pounds
Long-Term Debt [Abstract]
Spot rate	1.53	1.53		1.53
Euro Member Countries, Euro
Long-Term Debt [Abstract]
Spot rate	1.10	1.10		1.10
Total $8.0 Billion Debt Issuance [Member]
Long-Term Debt [Abstract]
Net proceeds from notes payable		$ 7,900
Total issuance costs		44
Fair value of the notes	$ 8,000	8,000
Maximum aggregate outstanding amount of indebtedness	$ 2,000	$ 2,000
Percentage of principal amount of fixed rate notes can be redeemed (in hundredths)		100.00%
Redemption of notes description		Redemption price equal to the greater of: (1) 100% of the principal amount of the fixed rate notes being redeemed; and (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon (not including any portion of such payments of interest accrued as of the redemption date), discounted to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the applicable series of notes), plus 15 basis points for the notes due 2017, 15 basis points for the notes due 2019, 20 basis points for the notes due 2021, 20 basis points for the notes due 2024, 20 basis points for the notes due 2034 and 25 basis points for the notes due 2044.
Percentage of redemption price (in hundredths)		100.00%
Percentage of principal amount required on triggering event to repurchase notes (in hundredths) | $ / €	101.00%	101.00%		101.00%
Total $4.0 Billion Debt Issuance [Member]
Long-Term Debt [Abstract]
Net proceeds from notes payable		$ 4,000
Total issuance costs		26
Fair value of the notes	$ 2,700	$ 2,700				3,400
Percentage of principal amount of fixed rate notes can be redeemed (in hundredths)		100.00%
Redemption of notes description		Redemption price equal to the greater of: (a) 100% of the principal amount of the notes being redeemed; and (b) the sum of the present values of the remaining scheduled payments of principal and interest thereon (not including any portion of such payments of interest accrued as of the date of redemption), discounted to the date of redemption on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the applicable series of notes), plus 12 basis points for the notes due 2015, 20 basis points for the notes due 2017, 22 basis points for the notes due 2022 and 25 basis points for the notes due 2042.
Percentage of redemption price (in hundredths)		100.00%
Percentage of principal amount required on triggering event to repurchase notes (in hundredths) | $ / €	101.00%	101.00%		101.00%
Total $1.0 Billion Debt Issuance [Member]
Long-Term Debt [Abstract]
Net proceeds from notes payable		$ 1,000
Total issuance costs		8
Fair value of the notes	$ 1,100	$ 1,100				$ 1,100
Stated interest rate (in hundredths)	5.25%	5.25%		5.25%
Interest payment frequency		semiannually in arrears on January 15 and July 15
Percentage of principal amount of fixed rate notes can be redeemed (in hundredths)		100.00%
Redemption of notes description		Redemption price equal to the greater of: (a) 100% of the principal amount of the notes to be redeemed; or (b) the sum of the present values of the remaining scheduled payments of principal and interest, discounted to the date of redemption on a semiannual basis at the Treasury Rate (as defined in the applicable series of notes), plus 45 basis points, plus accrued interest on the notes to be redeemed to, but excluding, the date of redemption.
Percentage of principal amount required on triggering event to repurchase notes (in hundredths) | $ / €	101.00%	101.00%		101.00%
Total $1.0 Billion Debt Issuance [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.45%
Euro and Pound Sterling Notes [Member]
Long-Term Debt [Abstract]
Total issuance costs		$ 11
Fair value of the notes	$ 1,900	1,900
Maximum aggregate outstanding amount of indebtedness	$ 2,000	$ 2,000
Redemption of notes description		Redemption price equal to the greater of: (1) 100% of the principal amount of the notes to be redeemed; and (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon (not including any portion of such payments of interest accrued as of the redemption date), discounted to the redemption date on an annual basis at the applicable Comparable Government Bond Rate, (as defined in the applicable series of notes), plus 20 basis points for the Euro notes, 20 basis points for the Pound Sterling notes due 2020 and 20 basis points for Pound Sterling the notes due 2025.
Percentage of redemption price (in hundredths) | $ / €		100.00%
Percentage of principal amount required on triggering event to repurchase notes (in hundredths) | $ / €	101.00%	101.00%		101.00%
Euro and Pound Sterling Notes [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
Unsecured Variable Rate Notes Due 2016 [Member]
Long-Term Debt [Abstract]
Debt instrument, description of variable rate basis		Three-month U.S. Dollar LIBOR
Unsecured Variable Rate Notes Due 2016 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.45%
1.750% Unsecured Notes Due 2017 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time in whole or from time to time in part
1.750% Unsecured Notes Due 2017 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.15%
2.700% Unsecured Notes Due 2019 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time prior to October 18, 2019 in whole or from time to time prior to October 18, 2019 in part
2.700% Unsecured Notes Due 2019 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.15%
3.300% Unsecured Notes Due 2021 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time prior to September 18, 2021 in whole or from time to time prior to September 18, 2021 in part
3.300% Unsecured Notes Due 2021 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
3.800% Unsecured Notes Due 2024 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time prior to August 18, 2024 in whole or from time to time prior to August 18, 2024 in part
3.800% Unsecured Notes Due 2024 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
4.500% Unsecured Notes Due 2034 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time prior to May 18, 2034 in whole or from time to time prior to May 18, 2034 in part
4.500% Unsecured Notes Due 2034 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
4.800% Unsecured Notes Due 2044 [Member]
Long-Term Debt [Abstract]
Redemption of notes description		At any time prior to May 18, 2044 in whole or from time to time prior to May 18, 2044 in part
4.800% Unsecured Notes Due 2044 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.25%
Notes Due 2014 [Member]
Long-Term Debt [Abstract]
Repayment of debt		$ 550
1.000% Unsecured Notes Due 2015 [Member]
Long-Term Debt [Abstract]
Repayment of debt		$ 750
1.000% Unsecured Notes Due 2015 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.12%
1.800% Unsecured Notes Due 2017 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
3.100% Unsecured Notes Due 2022 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.22%
4.400% Unsecured Notes Due 2042 [Member] | Treasury Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.25%
Unsecured Pound Sterling Notes Due 2020 [Member]
Long-Term Debt [Abstract]
Stated interest rate (in hundredths)	2.875%	2.875%		2.875%
Unsecured Pound Sterling Notes Due 2020 [Member] | Government Bond Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
Unsecured Pound Sterling Notes Due 2025 [Member]
Long-Term Debt [Abstract]
Stated interest rate (in hundredths)	3.60%	3.60%		3.60%
Unsecured Pound Sterling Notes Due 2025 [Member] | Government Bond Rate [Member]
Long-Term Debt [Abstract]
Basis spread on variable rate (in hundredths)		0.20%
Variable Rate Borrowings [Member]
Long-Term Debt [Abstract]
Other short-term borrowings	$ 46	$ 46
Term Loan [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,200	2,200		£ 1,450
Amount borrowed | £				£ 1,450
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,250	$ 2,250
Term of facility		5 years
Revolving Credit Facility [Member] | Upon the affirmative vote [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	3,000	$ 3,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	375	375
Letter of Credit [Member] | Upon the affirmative vote [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	500	500
Term loan and revolving credit agreement [Member]
Line of Credit Facility [Line Items]
Fees related to borrowings	14	14
364-Day Credit Agreement [Member]
Line of Credit Facility [Line Items]
Amount borrowed	$ 750	$ 750