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PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Tables) | 6 Months Ended
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Jun. 30, 2016
PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS |
Summary of the components of net periodic benefit cost |
|  | Three Months Ended June 30 |
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
|  | (in thousands) |
Service cost |  | $ | — |  | $ | — |  | $ | — |  | $ | — |  | $ | 107 |  | $ | 102 |
Interest cost |  |  | 1,158 |  |  | 1,223 |  |  | 33 |  |  | 30 |  |  | 255 |  |  | 229 |
Expected return on plan assets |  |  | (2,158) |  |  | (2,359) |  |  | — |  |  | — |  |  | — |  |  | — |
Amortization of prior service credit |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (48) |  |  | (48) |
Pension settlement expense |  |  | 564 |  |  | 597 |  |  | — |  |  | — |  |  | — |  |  | — |
Amortization of net actuarial loss(1) |  |  | 1,061 |  |  | 815 |  |  | 38 |  |  | 40 |  |  | 176 |  |  | 213 |
Net periodic benefit cost |  | $ | 625 |  | $ | 276 |  | $ | 71 |  | $ | 70 |  | $ | 490 |  | $ | 496 |
|  | Six Months Ended June 30 |
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
|  | (in thousands) |
Service cost |  | $ | — |  | $ | — |  | $ | — |  | $ | — |  | $ | 214 |  | $ | 203 |
Interest cost |  |  | 2,463 |  |  | 2,543 |  |  | 65 |  |  | 61 |  |  | 509 |  |  | 457 |
Expected return on plan assets |  |  | (4,104) |  |  | (4,761) |  |  | — |  |  | — |  |  | — |  |  | — |
Amortization of prior service credit |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (95) |  |  | (95) |
Pension settlement expense |  |  | 1,464 |  |  | 1,716 |  |  | — |  |  | — |  |  | — |  |  | — |
Amortization of net actuarial loss(1) |  |  | 2,017 |  |  | 1,636 |  |  | 76 |  |  | 80 |  |  | 352 |  |  | 426 |
Net periodic benefit cost |  | $ | 1,840 |  | $ | 1,134 |  | $ | 141 |  | $ | 141 |  | $ | 980 |  | $ | 991 |
| (1) |  | The Company amortizes actuarial losses over the average remaining active service period of the plan participants and does not use a corridor approach.
Schedule of changes in the projected benefit obligation and plan assets of the nonunion defined benefit pension plan |
|  | Nonunion Defined
|  | Benefit Pension Plan
|  | (in thousands)
Change in benefit obligations |  |  |  |
Benefit obligations at December 31, 2015 |  | $ | 159,607 |
Interest cost |  |  | 2,463 |
Actuarial loss(1) |  |  | 9,377 |
Benefits paid |  |  | (7,420) |
Benefit obligations at June 30, 2016 |  |  | 164,027 |
Change in plan assets |  |  |  |
Fair value of plan assets at December 31, 2015 |  |  | 136,917 |
Actual return on plan assets |  |  | 4,587 |
Employer contributions |  |  | 13,400 |
Benefits paid |  |  | (7,420) |
Fair value of plan assets at June 30, 2016 |  |  | 147,484 |
Funded status at June 30, 2016(2) |  | $ | (16,543) |
Accumulated benefit obligation |  | $ | 164,027 |
| (1) |  | Actuarial loss from remeasurement upon settlement was primarily impacted by the change in the discount rate since the previous remeasurement date. The discount rates used to remeasure the PBO upon settlement were 2.7%, 3.0%, and 3.5% at the June 30, 2016, March 31, 2016, and December 31, 2015 measurement date, respectively.
| (2) |  | Noncurrent liability recognized within pension and postretirement liabilities in the accompanying consolidated balance sheet at June 30, 2016.

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- Definition Tabular disclosure of net funded status of pension plans and/or other employee benefit plans and disclosure of accumulated benefit obligation. + References No definition available. + Details
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- References No definition available. + Details
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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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