EMPLOYEE BENEFIT PLANS Table 1 - Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Pension Plan [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Service cost | $ 2,406 | $ 2,239 |
| Interest cost | 1,206 | 1,127 |
| Expected return on assets | (1,855) | (1,603) |
| Amortization of prior service credit | (514) | (515) |
| Amortization of net loss | 544 | 371 |
| Net periodic benefit cost (income) | 1,787 | 1,619 |
| Other Postretirement Benefits Plan [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Service cost | 126 | 113 |
| Interest cost | 108 | 108 |
| Expected return on assets | 0 | 0 |
| Amortization of prior service credit | (287) | (286) |
| Amortization of net loss | 54 | 48 |
| Net periodic benefit cost (income) | $ 1 | $ (17) |