EMPLOYEE BENEFIT PLANS Table 2 - Components of Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member] | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Service cost | $ 8,955 | $ 7,703 | $ 7,676 |
| Interest cost | 4,507 | 4,023 | 4,389 |
| Expected return on plan assets | (6,411) | (5,407) | (5,018) |
| Amortization of prior service credit | (2,059) | (2,063) | (2,063) |
| Amortization of net actuarial loss | 1,484 | 1,091 | 1,845 |
| Net periodic benefit cost (income) | 6,476 | 5,347 | 6,829 |
| Other Postretirement Benefits Plan [Member] | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Service cost | 456 | 419 | 470 |
| Interest cost | 430 | 401 | 448 |
| Expected return on plan assets | 0 | 0 | 0 |
| Amortization of prior service credit | (1,145) | (1,145) | (1,145) |
| Amortization of net actuarial loss | 191 | 181 | 269 |
| Net periodic benefit cost (income) | $ (68) | $ (144) | $ 42 |