FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring basis (Details) - Other Long Term Liabilities [Member] - USD ($) $ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Liabilities | ||
| Deferred Compensation | $ (40,170) | $ (40,995) |
| Fair Value, Inputs, Level 1 [Member] | ||
| Liabilities | ||
| Deferred Compensation | (24,791) | (23,751) |
| Fair Value, Inputs, Level 2 [Member] | ||
| Liabilities | ||
| Deferred Compensation | 0 | 0 |
| Fair Value, Inputs, Level 3 [Member] | ||
| Liabilities | ||
| Deferred Compensation | 0 | 0 |
| Measured at Net Asset Value as Practical Expedient [Member] | ||
| Liabilities | ||
| Deferred Compensation | $ (15,379) | $ (17,244) |