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Employee Benefits - U.S. and Canadian Other Post-Retirement Benefits Narrative (Details) - U.S. and Canadian Other Post-Retirement Benefits - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Unrecognized prior-service cost | $ 1.0 | $ 3.0
Future amortization of gain | 1.4 |
Future amortization of prior service credit | 0.1 |
Expected employer contributions during next fiscal year | 4.0 |
Expected future benefit payments 2018 | 4.0 |
Expected future benefit payments 2019 | 0.0 |
Expected future benefit payments 2020 | 0.0 |
Expected future benefit payments 2021 | 0.0 |
Expected future benefit payments 2022 | 0.0 |
Expected future benefit payments 2023-2027 | 194.0 |
Effect of one percentage point increase on accumulated postretirement benefit obligation | 6.0 |
Effect of one percentage point decrease on accumulated postretirement benefit obligation | 5.0 |
Effect of one percentage point increase on service cost and interest cost components of net periodic benefit cost | 0.5 |
Effect of one percentage point decrease on service cost and interest cost components of net periodic benefit cost | $ 0.5 |
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage | 5.00% |
Maximum percentage of medical supplement plan into future periods | 5.00% |
Maximum |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage | 9.00% |
Minimum |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage | 4.00% |

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- Definition Defined Benefit Plan Maximum Percentage of Medical Supplement Plan Into Future Periods + References No definition available. + Details
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- Definition Represents the percentage of medical supplement plan coverage for defined benefit plan. + References No definition available. + Details
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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate. + 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 (m) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate. + 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 (m) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position. + 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 (s) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount included in accumulated other comprehensive (income) loss for prior service cost (credit) expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position. + 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 (s) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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