v3.21.2
Retirement Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 12 Months Ended
May 31, 2021
May 31, 2020
May 31, 2019
Pension Plans [Member] | U.S. Plans [Member]      
Net Periodic Benefit Cost      
Service cost $ 851 $ 768 $ 689
Interest cost 959 1,000 951
Expected return on plan assets (1,786) (1,601) (1,505)
Amortization of prior service credit (8) (105) (118)
Actuarial (gains) losses and other (1,288) 888 3,537
Net periodic benefit cost (1,272) 950 3,554
Pension Plans [Member] | International Pension Plans [Member]      
Net Periodic Benefit Cost      
Service cost 83 96 94
Interest cost 43 43 49
Expected return on plan assets (52) (51) (46)
Amortization of prior service credit (2) (2) (2)
Actuarial (gains) losses and other (13) (179) 80
Net periodic benefit cost 59 (93) 175
Postretirement Healthcare Plans [Member]      
Net Periodic Benefit Cost      
Service cost 44 42 35
Interest cost 39 44 40
Actuarial (gains) losses and other 125 85 265
Net periodic benefit cost $ 208 $ 171 $ 340