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PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Tables) | 9 Months Ended
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Sep. 30, 2019
PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS |
Summary of the components of net periodic benefit cost | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three Months Ended September 30 | ​
​ | ​ | Nonunion Defined | ​ | Supplemental | ​ | Postretirement | ​
​ | ​ | Benefit Pension Plan | ​ | Benefit Plan | ​ | Health Benefit Plan | ​
​ |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |
​ | ​ | (in thousands) | ​
Service cost | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | 80 | ​ | $ | 92 | ​
Interest cost | ​ |  | 138 | ​ |  | 1,136 | ​ |  | 9 | ​ |  | 27 | ​ |  | 303 | ​ |  | 209 | ​
Expected return on plan assets | ​ |  | 29 | ​ |  | (363) | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​
Amortization of prior service credit | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | (8) | ​ |  | (23) | ​
Pension settlement expense(1) | ​ |  | 2,530 | ​ |  | 518 | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​
Amortization of net actuarial loss(2) | ​ |  | 50 | ​ |  | 494 | ​ |  | 24 | ​ |  | 20 | ​ |  | 225 | ​ |  | 76 | ​
Net periodic benefit cost | ​ | $ | 2,747 | ​ | $ | 1,785 | ​ | $ | 33 | ​ | $ | 47 | ​ | $ | 600 | ​ | $ | 354 | ​
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Nine Months Ended September 30 | ​
​ | ​ | Nonunion Defined | ​ | Supplemental | ​ | Postretirement | ​
​ | ​ | Benefit Pension Plan | ​ | Benefit Plan | ​ | Health Benefit Plan | ​
​ |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |
​ | ​ | (in thousands) | ​
Service cost | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | 240 | ​ | $ | 275 | ​
Interest cost | ​ |  | 624 | ​ |  | 3,259 | ​ |  | 29 | ​ |  | 81 | ​ |  | 909 | ​ |  | 628 | ​
Expected return on plan assets | ​ |  | (60) | ​ |  | (1,142) | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​
Amortization of prior service credit | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | (25) | ​ |  | (70) | ​
Pension settlement expense(1) | ​ |  | 4,164 | ​ |  | 1,603 | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​
Amortization of net actuarial loss(2) | ​ |  | 260 | ​ |  | 1,864 | ​ |  | 71 | ​ |  | 60 | ​ |  | 674 | ​ |  | 228 | ​
Net periodic benefit cost | ​ | $ | 4,988 | ​ | $ | 5,584 | ​ | $ | 100 | ​ | $ | 141 | ​ | $ | 1,798 | ​ | $ | 1,061 | ​
​
(1) | The presentation of net periodic pension cost for the three and nine months ended September 30, 2019 excludes a $4.0 million noncash pension termination expense which is further described within this Note.
(2) | 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, 2018 | ​ | $ | 33,373 | ​
Interest cost | ​ |  | 624 | ​
Actuarial loss(1) | ​ |  | 300 | ​
Benefits paid | ​ |  | (34,297) | ​
Benefit obligations at September 30, 2019 | ​ |  | — | ​
Change in plan assets | ​ | ​ | ​ | ​
Fair value of plan assets at December 31, 2018 | ​ |  | 26,646 | ​
Actual return on plan assets | ​ |  | (30) | ​
Employer contributions | ​ |  | 7,710 | ​
Benefits paid | ​ |  | (34,297) | ​
Fair value of plan assets at September 30, 2019 | ​ |  | 29 | ​
Funded status at period end(2) | ​ | $ | 29 | ​
​ | ​ | ​ | ​ | ​
Accumulated benefit obligation | ​ | $ | — | ​
​
(1) | The plan recognized an actuarial loss related to the settlement of benefit obligations for missing participants which were transferred to the PBGC, partially offset by an actuarial gain related to the difference between the actual amounts distributed for lump-sum benefits and the annuity contract purchase versus the actuarial estimates made for these obligations as of the December 31, 2018 measurement date.
(2) | Recognized within other current assets in the accompanying consolidated balance sheet at September 30, 2019.

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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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- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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