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Pension Plans and Other Benefits - Fair Value Assumptions (Details) - North American Pension Plans | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
The assumptions used to determine benefit obligations were as follows: |  |  |  |
Discount rate |  | 4.09% | 3.51% | 3.97%
Expected return on plan assets |  | 5.14% | 5.54% | 5.54%
Rate of compensation increase |  | 3.50% | 3.50% | 3.50%
The assumptions used to determine net benefit cost were as follows: |  |  |  |
Discount rate |  | 3.51% | 3.97% | 4.17%
Service cost discount rate | [1] | 3.50% | 4.02% | 4.19%
Interest cost discount rate | [1] | 3.21% | 3.44% | 3.45%
Expected return on plan assets |  | 5.54% | 5.54% | 5.66%
Rate of compensation increase |  | 3.50% | 3.50% | 3.50%
[1] | In 2016, we changed the method used to estimate the service and interest cost components of net periodic benefit cost for our defined benefit pension and other postretirement benefit plans by electing a full yield curve approach and applying the specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flows. The impact of this change to our earnings and earnings per share was not material.

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- Definition An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested used for calculating the benefit obligation. + References No definition available. + Details
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- Definition The interest rate used to adjust the interest cost component of the net periodic benefit cost for the time value of money. + References No definition available. + Details
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- Definition The interest rate used to adjust the service cost component of the net periodic benefit cost for the time value of money. + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + 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 (k)(1) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + 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 (k)(2) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + 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 (k)(1) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + 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 (k)(3) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + 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 (k)(2) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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