Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Percentage of plan assets to benefit obligation of defined benefit plan.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from event reducing expected years of future service of present employees or eliminating accrual of defined benefits for some or all future services of present employees.

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Amount of cost for defined contribution plan.

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

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The amount of the cost recognized during the period for defined contribution plans profit sharing provision benefit expense amount.

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Retirement benefits - additional information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Aug. 31, 2018	May 31, 2017	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plan, investments holding percentage	85.00%		85.00%
Cash contributions to defined benefit pension plans			$ 29
Profit sharing provision expense			217	$ 221	$ 226
Contributions to profit sharing			366	220	225
Cost recognized in the consolidated condensed statements of earnings			142	112	$ 130
Postretirement Health Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, benefit obligation, period increase (decrease)	$ 201
Curtailment gain	112	$ 109
Defined benefit plan obligation	146		146	$ 361
Expected benefit to be paid net of estimated federal subsidy during fiscal year 2017	$ 11		$ 11