Long-Term Debt - Schedule (Details) - Notes Payable - USD ($)	Aug. 31, 2020	May 31, 2020
Debt Instrument [Line Items]
Debt instrument, face amount	$ 4,000,000,000	$ 8,000,000,000
Floating rate notes due 2023
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000,000	300,000,000
1.141% Notes due 2023
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.141%
Debt instrument, face amount		1,200,000,000
1.554% Notes due 2025
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.554%
Debt instrument, face amount		2,500,000,000
1.995% Notes due 2027
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.995%
Debt instrument, face amount		1,000,000,000
2.236% Notes due 2030
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.236%
Debt instrument, face amount		1,500,000,000
2.978% Notes due 2040
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.978%
Debt instrument, face amount		500,000,000
3.078% Notes due 2050
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.078%
Debt instrument, face amount		$ 1,000,000,000
Floating rate notes due 2022
Debt Instrument [Line Items]
Debt instrument, face amount	$ 350,000,000
0.333% notes due 2022
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.333%
Debt instrument, face amount	$ 400,000,000
0.426% notes due 2023
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.426%
Debt instrument, face amount	$ 500,000,000
0.687% notes due 2025
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.687%
Debt instrument, face amount	$ 750,000,000
1.018% notes due 2027
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.018%
Debt instrument, face amount	$ 750,000,000
2.343% notes due 2050
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.343%
Debt instrument, face amount	$ 750,000,000