Retirement benefits (Tables)

3 Months Ended

Nov. 30, 2017

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Cost

Components of net periodic pension costs for the defined benefit pension plans (in millions):

	Three months ended November 30,
	2017			2016
Service costs	$	2		$	2
Interest costs	47			43
Expected returns on plan assets	(51		)	(37		)
Total net periodic pension costs	$	(2	)	$	8