Debt - Short and Long-Term Debt (Details) - USD ($) $ in Millions	9 Months Ended
	May 31, 2018	Aug. 31, 2017
Debt Instrument [Line Items]
Total short-term debt	$ 2,587	$ 251
Other	27	24
Total long-term debt, less current portion	12,456	12,684
Other Short Term Debt
Debt Instrument [Line Items]
Total short-term debt	301	251
Unsecured Notes | 3.450% unsecured notes due 2026
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,888	1,887
Stated interest rate	3.45%
Maturity year	2026
Unsecured Notes | 4.650% unsecured notes due 2046
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 590	590
Stated interest rate	4.65%
Maturity year	2046
Unsecured Notes | 2.700% unsecured notes due 2019
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,247	1,246
Stated interest rate	2.70%
Maturity year	2019
Unsecured Notes | 3.300% unsecured notes due 2021
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,245	1,244
Stated interest rate	3.30%
Maturity year	2021
Unsecured Notes | 3.800% unsecured notes due 2024
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,989	1,988
Stated interest rate	3.80%
Maturity year	2024
Unsecured Notes | 4.500% unsecured notes due 2034
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 495	495
Stated interest rate	4.50%
Maturity year	2034
Unsecured Notes | 4.800% unsecured notes due 2044
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,492	1,492
Stated interest rate	4.80%
Maturity year	2044
Unsecured Notes | 2.875% unsecured Pound sterling notes due 2020
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 530	513
Stated interest rate	2.875%
Maturity year	2020
Unsecured Notes | 3.600% unsecured Pound sterling notes due 2025
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 397	384
Stated interest rate	3.60%
Maturity year	2025
Unsecured Notes | 2.125% unsecured Euro notes due 2026
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 869	884
Stated interest rate	2.125%
Maturity year	2026
Unsecured Notes | 3.100% unsecured notes due 2022
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,195	1,195
Stated interest rate	3.10%
Maturity year	2022
Unsecured Notes | 4.400% unsecured notes due 2042
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 492	492
Stated interest rate	4.40%
Maturity year	2042
Unsecured Notes | 5.250% unsecured notes due 2019
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 0	250
Stated interest rate	5.25%
Maturity year	2019
Commercial paper
Debt Instrument [Line Items]
Total short-term debt	$ 1,039	0
Credit facilities
Debt Instrument [Line Items]
Total short-term debt	999	0
Notes Payable | 5.250% unsecured notes due 2019
Debt Instrument [Line Items]
Total short-term debt	$ 248	$ 0
Stated interest rate	5.25%
Maturity year	2019