Operating leases (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Aug. 31, 2018
Leases [Abstract]
Charges related to facilities that were closed or relocated	$ 13	$ 39
Changes in reserve for facility closings and related lease termination charges [Roll Forward]
Balance at beginning of period	964	$ 718	$ 718
Provision for present value of non-cancellable lease payments on closed facilities	(3)		52
Changes in assumptions	(2)		19
Accretion expense	18		58
Other - non cash	77		338
Cash payments, net of sublease income	(84)		(221)
Balance at end of period	$ 970		$ 964