INCOME TAXES (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Nov. 30, 2019 |
Nov. 30, 2018 |
Nov. 30, 2019 |
Nov. 30, 2018 |
May 31, 2019 |
|
| Income Tax Disclosure [Abstract] | |||||
| Effective income tax rate | 17.70% | 15.90% | 16.00% | 13.50% | |
| Income tax net benefit, adjustments to estimate of U.S. Tax Cuts and Jobs Act of 2017 one-time transition tax and remeasurement of net deferred tax assets and liabilities | $ 153 | ||||
| Deferred Tax Assets, Net [Abstract] | |||||
| Net deferred tax assets | $ 2,600 | $ 2,600 | $ 2,400 | ||