EMPLOYEE BENEFIT PLANS Table 1 - Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Pension Plan [Member] | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | $ 2,405 | $ 2,239 | $ 4,811 | $ 4,478 |
| Interest cost | 1,206 | 1,127 | 2,412 | 2,254 |
| Expected return on assets | (1,854) | (1,602) | (3,709) | (3,205) |
| Amortization of prior service credit | (514) | (516) | (1,028) | (1,031) |
| Amortization of net loss | 543 | 371 | 1,087 | 742 |
| Net periodic benefit cost (income) | 1,786 | 1,619 | 3,573 | 3,238 |
| Other Postretirement Benefits Plan [Member] | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 126 | 113 | 252 | 226 |
| Interest cost | 107 | 108 | 215 | 216 |
| Expected return on assets | 0 | 0 | 0 | 0 |
| Amortization of prior service credit | (286) | (286) | (573) | (572) |
| Amortization of net loss | 53 | 48 | 107 | 96 |
| Net periodic benefit cost (income) | $ 0 | $ (17) | $ 1 | $ (34) |