SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN - Components of Net Periodic Pension Cost (Details) - Supplemental Executive Retirement Plan [Member] - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Components of net periodic pension cost [Abstract] | ||||
| Service cost | $ 354 | $ 319 | $ 1,062 | $ 867 |
| Interest cost | 219 | 166 | 656 | 452 |
| Amortization of prior service cost | 415 | 436 | 1,245 | 1,114 |
| Amortization of loss | 3 | 11 | ||
| Total net periodic benefit cost | $ 991 | $ 921 | $ 2,974 | $ 2,433 |