FAIR VALUE MEASUREMENTS Narrative (Details) - USD ($) $ in Billions |
3 Months Ended | |
|---|---|---|
Aug. 31, 2017 |
May 31, 2017 |
|
| Marketable security investments maturity information [Abstract] | ||
| Maturity of marketable security investments | As of August 31, 2017 and May 31, 2017, approximately 28% and 32%, respectively, of our marketable securities investments mature within one year and 72% and 68%, respectively, mature within one to six years. | |
| Percentage of marketable securities investments mature within one year | 28.00% | 32.00% |
| Percentage of marketable securities investments mature within one to six years | 72.00% | 68.00% |
| Short and Long Term Debt [Abstract] | ||
| Senior notes | $ 53.1 | $ 54.0 |
| Fair Value Measurements Using Input Types Level 2 [Member] | ||
| Liabilities [Abstract] | ||
| Total debt fair value | $ 55.9 | $ 56.5 |