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BENEFIT PLANS: (Tables) | 12 Months Ended
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Dec. 31, 2019
Post retirement defined benefit plans and defined contribution plan |
Components of net periodic benefit costs |
Schedule of the components of net periodic benefit costs | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
(in millions) |  | 2019 |  | 2018 |  | 2017
Service cost | ​ | $ | 1.1 | ​ | $ | 1.0 | ​ | $ | 0.8
Interest cost | ​ |  | 1.8 | ​ |  | 1.6 | ​ |  | 1.4
Expected return on plan assets | ​ |  | (3.5) | ​ |  | (3.4) | ​ |  | (2.9)
Amortization of prior service cost / (credit) | ​ |  | 0.2 | ​ |  | 0.2 | ​ |  | 0.1
Settlement / Curtailment | ​ | ​ | — | ​ | ​ | (0.2) | ​ | ​ | 0.1
Amortization of net loss/(gain) | ​ |  | 0.3 | ​ |  | 0.2 | ​ |  | 0.2
Net periodic benefit cost | ​ | $ | (0.1) | ​ | $ | (0.6) | ​ | $ | (0.3)
Schedule of changes in the benefit obligation and plan assets, the funded status of the plans and the amount recognized in balance sheet and accumulated other comprehensive income | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of December 31,
(in millions) |  | 2019 |  | 2018
Change in benefit obligation: | ​ | ​ | ​ | ​ | ​ | ​
Projected benefit obligation at beginning of year | ​ | $ | 27.4 | ​ | $ | 27.5
Service cost | ​ |  | 1.1 | ​ |  | 1.0
Interest cost | ​ |  | 1.8 | ​ |  | 1.6
Settlement | ​ |  | — | ​ |  | —
Benefits paid | ​ |  | (1.8) | ​ |  | (1.6)
Actuarial (gain)/loss | ​ |  | 3.6 | ​ |  | (0.2)
Actuarial gain assumption changes | ​ |  | 0.9 | ​ |  | (0.8)
Inflation adjustment | ​ |  | 0.7 | ​ |  | (0.1)
Projected benefit obligation at end of year | ​ | $ | 33.7 | ​ | $ | 27.4
Change in plan assets: | ​ | ​ | ​ | ​ | ​ | ​
Fair value of plan assets at beginning of year | ​ | $ | 46.7 | ​ | $ | 51.6
Actual return on plan assets | ​ |  | 4.8 | ​ |  | (3.5)
Employer contributions | ​ |  | (0.6) | ​ |  | (0.4)
Benefits paid | ​ |  | (0.9) | ​ |  | (1.0)
Currency exchange rate adjustment | ​ |  | 1.6 | ​ |  | —
Fair value of plan assets at end of year | ​ | $ | 51.6 | ​ | $ | 46.7
Funded status at end of year: | ​ | $ | 17.9 | ​ | $ | 19.3
ASC-715 amounts recognized in statement of financial position consists of: | ​ | ​ | ​ | ​ | ​ | ​
Non-current assets | ​ | $ | 17.9 | ​ | $ | 19.4
Total | ​ | $ | 17.9 | ​ | $ | 19.4
ASC-715 amounts recognized in accumulated other comprehensive income (net of income taxes of $(5.4) million and $(4.3) million in 2019 and 2018, respectively) consists of: | ​ | ​ | ​ | ​ | ​ | ​
Net loss (gain) | ​ | $ | 7.6 | ​ | $ | 5.8
Prior service cost | ​ |  | 1.4 | ​ |  | 1.4
Total | ​ | $ | 9.0 | ​ | $ | 7.2
Schedule of changes in accumulated other comprehensive income | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
(in millions) |  | 2019 |  | 2018
Reconciliation of accumulated other comprehensive income: | ​ | ​ | ​ | ​ | ​ | ​
Accumulated other comprehensive income at beginning of plan year | ​ | $ | 7.2 | ​ | $ | 3.8
Net loss/(gain) amortized during the year | ​ |  | 1.9 | ​ |  | 3.6
Net loss/(gain) occurring during the year | ​ |  | (0.2) | ​ |  | (0.1)
Prior service cost (credit) | ​ | ​ | — | ​ | ​ | —
Currency exchange rate adjustment | ​ |  | 0.1 | ​ |  | (0.1)
Net adjustment to accumulated other comprehensive income (net of income taxes of $(2.2) million and $(2.2) million in 2019 and 2018, respectively) | ​ |  | 1.8 | ​ |  | 3.4
Accumulated other comprehensive income at end of plan year | ​ | $ | 9.0 | ​ | $ | 7.2
Summary of the amounts in accumulated other comprehensive income amortized and recognized as a component of net periodic benefit cost, net of tax | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
(in millions) |  | 2019 |  | 2018
Net loss / (gain) | ​ | $ | 1.8 | ​ | $ | 3.6
Amortization of net (loss) gain | ​ |  | (0.2) | ​ |  | (0.1)
Amortization of prior services cost (credit) | ​ | ​ | — | ​ | ​ | —
Total amortization expenses | ​ | $ | 1.6 | ​ | $ | 3.5
Schedule of assumptions used to determine the pension obligations and other post-retirement benefits | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Expatriate Plan |  | 2019 |  | 2018 |  | 2017 |
Discount rate |  | 2.85 | % | 3.90 | % | 3.25 | %
Expected long-term rate of return on plan asset |  | 4.00 | % | 4.00 | % | 4.00 | %
Rate of increase in future compensation level |  | N/A | ​ | N/A | ​ | N/A | ​
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Mexican Plan(*) |  | 2019 |  | 2018 |  | 2017 |
Discount rate |  | 7.15 | % | 8.45 | % | 7.80 | %
Expected long-term rate of return on plan asset |  | 7.15 | % | 8.45 | % | 7.55 | %
Rate of increase in future compensation level |  | 4.50 | % | 4.50 | % | 4.50 | %
(*)These rates are based on Mexican pesos as pension obligations are denominated in pesos.
Scheduled maturities of the benefits expected to be paid in each of the next five years, and thereafter | ​
​ | ​ | ​ | ​
​ |  | Expected
Years | ​ | Benefit Payments
​ | ​ | (in millions)
2020 | ​ | $ | 3.2
2021 | ​ |  | 1.9
2022 | ​ |  | 2.0
2023 | ​ |  | 2.0
2024 | ​ |  | 2.3
2025 to 2027 | ​ |  | 14.7
Total | ​ | $ | 26.1
​
Post-retirement Health care plans |
Components of net periodic benefit costs |
Schedule of the components of net periodic benefit costs | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
(in millions) |  | 2019 |  | 2018 |  | 2017
Interest cost | ​ | $ | 0.9 | ​ | $ | 0.9 | ​ | $ | 0.9
Amortization of prior service cost/ (credit) | ​ |  | (0.2) | ​ |  | (0.2) | ​ |  | (0.2)
Net periodic benefit cost | ​ | $ | 0.7 | ​ | $ | 0.7 | ​ | $ | 0.7
​
Schedule of changes in the benefit obligation and plan assets, the funded status of the plans and the amount recognized in balance sheet and accumulated other comprehensive income | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of December 31,
(in millions) |  | 2019 |  | 2018
Change in benefit obligation: | ​ | ​ | ​ | ​ | ​ | ​
Projected benefit obligation at beginning of year | ​ | $ | 11.9 | ​ | $ | 12.5
Interest cost | ​ |  | 0.9 | ​ |  | 0.9
Actuarial loss/ (gain)-claims cost | ​ |  | — | ​ |  | 0.2
Benefits paid | ​ |  | (1.3) | ​ |  | (0.9)
Actuarial (gain)/loss | ​ |  | 8.6 | ​ |  | (0.9)
Inflation adjustment | ​ |  | 0.5 | ​ |  | 0.1
Projected benefit obligation at end of year | ​ | $ | 20.6 | ​ | $ | 11.9
Change in plan assets: | ​ | ​ | ​ | ​ | ​ | ​
Fair value of plan assets at beginning of year | ​ | $ | — | ​ | $ | —
Employer contributions | ​ |  | 0.1 | ​ |  | 0.1
Benefits paid | ​ |  | (0.1) | ​ |  | (0.1)
Fair value of plan assets at end of year | ​ | $ | — | ​ | $ | —
Funded status at end of year: | ​ | $ | 20.6 | ​ | $ | 11.9
ASC-715 amounts recognized in statement of financial position consists of: | ​ | ​ | ​ | ​ | ​ | ​
Current liabilities | ​ | $ | (0.1) | ​ | $ | (0.1)
Non-current liabilities | ​ |  | (20.5) | ​ |  | (11.8)
Total | ​ | $ | (20.6) | ​ | $ | (11.9)
ASC-715 amounts recognized in accumulated other comprehensive income consists of: | ​ | ​ | ​ | ​ | ​ | ​
Net loss (gain) | ​ | $ | 1.5 | ​ | $ | (4.4)
Total (net of income taxes of $(0.7) million and $1.9 million in 2019 and 2018, respectively) | ​ | $ | 1.5 | ​ | $ | (4.4)
​
Schedule of changes in accumulated other comprehensive income | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of December 31,
(in millions) |  | 2019 |  | 2018
Reconciliation of accumulated other comprehensive income: | ​ | ​ | ​ | ​ | ​ | ​
Accumulated other comprehensive income at beginning of plan year | ​ | $ | (4.4) | ​ | $ | (3.9)
Net loss/(gain) occurring during the year | ​ |  | 6.0 | ​ |  | (0.6)
Net loss/(gain) amortized during the year | ​ |  | 0.1 | ​ |  | 0.1
Currency exchange rate adjustment | ​ |  | (0.2) | ​ |  | —
Net adjustment to accumulated other comprehensive income (net of income taxes of $(2.6) million and $0.2 million in 2019 and 2018, respectively) | ​ |  | 5.9 | ​ |  | (0.5)
Accumulated other comprehensive income at end of plan year | ​ | $ | 1.5 | ​ | $ | (4.4)
​
Summary of the amounts in accumulated other comprehensive income amortized and recognized as a component of net periodic benefit cost, net of tax | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of December 31,
(in millions) |  | 2019 |  | 2018
Net loss / (gain) | ​ | $ | 5.9 | ​ | $ | (0.6)
Amortization of net (loss) gain | ​ |  | 0.2 | ​ |  | 0.2
Total amortization expenses | ​ | $ | 6.1 | ​ | $ | (0.4)
​
Schedule of assumptions used to determine the pension obligations and other post-retirement benefits | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | 2019 |  | 2018 |  | 2017 |
Expatriate health plan | ​ | ​ | ​ | ​ | ​ | ​ | ​
Discount rate |  | 2.85 | % | 3.90 | % | 3.25 | %
Mexican health plan | ​ | ​ | ​ | ​ | ​ | ​ | ​
Weighted average discount rate |  | 7.15 | % | 8.45 | % | 7.80 | %
Scheduled maturities of the benefits expected to be paid in each of the next five years, and thereafter | ​
​ | ​ | ​ | ​
​ |  | Expected
Year | ​ | Benefit Payments
​ | ​ | (in millions)
2020 | ​ | $ | 1.3
2021 | ​ | ​ | 1.3
2022 | ​ |  | 1.3
2023 | ​ |  | 1.4
2024 | ​ |  | 1.4
2025 to 2029 | ​ |  | 7.3
Total | ​ | $ | 14.0
​
Mexican Health Plan | Post retirement defined benefit plans and defined contribution plan |
Components of net periodic benefit costs |
Schedule of asset mix of the investment portfolio | ​
​ | ​ | ​ | ​ | ​ | ​
​ |  | 2019 |  | 2018 |
Asset category: | ​ | ​ | ​ | ​ | ​
Treasury bills |  | 80 | % | 78 | %
Equity securities |  | 20 | % | 22 | %
​ |  | 100 | % | 100 | %
​
Mexican Health Plan | Post-retirement Health care plans |
Components of net periodic benefit costs |
Schedule of effects of one percentage-point change in assumed other benefits cost trend rates | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | One Percentage
​ | ​ | Point
(in millions) |  | Increase |  | Decrease
Effect on total service and interest cost components | ​ | $ | 1.4 | ​ | $ | 0.9
Effect on the post-retirement benefit obligation | ​ | $ | 18.8 | ​ | $ | 12.2

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- Definition Tabular disclosure of the change in the benefit obligation and fair value of the assets of pension plans from the beginning to the end of the period, showing separately, if applicable, the effects of the following: service cost, interest cost, contributions by plan participants, actuarial gains and losses, foreign currency exchange rate changes, benefits paid, plan amendments, business combinations, divestitures, curtailments, settlements, and special and contractual termination benefits. This also includes amount recognized in balance sheet and accumulated other comprehensive income. + References No definition available. + Details
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- Definition Tabular disclosure of the major categories of plan assets of pension plans and/or other employee benefit plans. This information may include, but is not limited to, the target allocation of plan assets, the fair value of each major category of plan assets, and the level within the fair value hierarchy in which the fair value measurements fall. + 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 (d)(5) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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