Retirement Plans - Additional Information (Details)	1 Months Ended	12 Months Ended
	May 31, 2018 USD ($) RetireeandBeneficiary	May 31, 2021 USD ($)	May 31, 2020 USD ($)	May 31, 2019 USD ($)	May 31, 2018 USD ($)	May 31, 2017
Defined Benefit Plan Disclosure [Line Items]
U.S. pension plan actual rate of return on assets			15.00%	4.05%	6.30%
Weighted average discount rate percent all pension postretirement plans			3.05%	3.69%	4.11%	3.98%
401(k)-plan description			In November 2019, we announced the closing of our U.S.-based defined benefit pension plans to new non-union employees hired on or after January 1, 2020. We will introduce an all-401(k)-plan retirement benefit structure for eligible employees with a higher company match of up to 8% across all U.S.-based operating companies. During 2021, current eligible employees under the PPA pension formula will be given a one-time option to continue to be eligible for pension compensation credits under the existing PPA formula and remain in the existing 401(k) plan with its company match of up to 3.5%, or to cease receiving compensation credits under the PPA and move to the new 401(k) plan with the higher match of up to 8%. Changes to the new 401(k) plan structure become effective beginning January 1, 2022. While this new program will provide employees greater flexibility and reduce our long-term pension costs, it will not have a material impact on current or near-term financial results.
Actual rate of return on plan assets for the 15-year period			7.70%
Amounts recognized in other comprehensive income primarily related to amortization of prior service cost, net of tax			$ 79,000,000	$ 92,000,000	$ 89,000,000
Defined benefit plan health care cost trend rate assumed for next fiscal year			5.70%
Defined benefit plan ultimate health care cost trend rate			4.50%
Defined benefit plan year that rate reaches ultimate trend rate			2037
Metropolitan Life Insurance Company [Member]
Defined Benefit Plan Disclosure [Line Items]
One-time settlement loss	$ 210,000,000
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer			$ 1,000,000,000	$ 1,000,000,000
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on assets			6.75%	6.75%	6.50%
Pension Plans [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on assets			6.75%	6.75%	6.50%
Defined benefit plan contributions by employer			$ 1,068,000,000	$ 1,034,000,000
Amounts recognized in other comprehensive income primarily related to amortization of prior service cost			105,000,000	118,000,000
Amounts recognized in other comprehensive income primarily related to amortization of prior service cost, net of tax			$ 80,000,000	$ 91,000,000
Pension Plans [Member] | U.S. Plans [Member] | Forecast
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		$ 0
Pension Plans [Member] | U.S. Plans [Member] | Metropolitan Life Insurance Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan responsibility transferred to number of retirees and beneficiaries | RetireeandBeneficiary	41,000
Group annuity contract and transfer	$ 6,000,000,000
Future Plan Structure [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Company matching contributions to eligible employees			8.00%
Current Plan Structure [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Company matching contributions to eligible employees			3.50%