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Pension Plans and Other Postretirement Benefits - Narrative (Details) - USD ($) shares in Millions, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2011 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Projected Retirement Benefit Expense In Next 12 months |  |  | $ 98.0 |  |  |
Defined contribution plan- Company contribution (percent) |  |  | 6.50% |  |  |
Defined contribution plan- Company matching contribution (percent) |  |  | 3.00% |  |  |
Other postretirement benefit costs for a defined contribution plan |  |  | $ 41.2 | $ 21.9 | $ 24.3 |
Projected future contributions to VEBA trusts |  |  | $ 7.0 |  |  |
US Qualified Plan [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Percentage of total assets |  |  | 96.00% |  |  |
Number of shares of equity securities issued by employer included in plan assets |  |  | 3.0 | 3.0 |  |
Fair value of employer equity securities included in plan assets |  |  | $ 33.2 | $ 102.7 |  |
Dividends on employer stock received by plan |  |  | 1.8 | 2.1 |  |
Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Projected Retirement Benefit Expense In Next 12 months |  |  | 64.0 |  |  |
One-time, voluntary lump sum payments |  |  |  | 52.0 |  |
Benefit obligation increase for changes in mortality assumptions |  |  |  | $ 90.0 |  |
Weighted average life expectancy |  |  |  | 18 years |  |
Average remaining service period |  |  |  | 10 years |  |
Accumulated benefit obligation |  |  | $ 2,767.0 | $ 2,917.3 |  |
Expected long-term rate of return on assets |  |  | 8.00% | 8.25% | 8.25% |
Actual return on plan assets | 0.30% |  | (1.20%) | 6.50% | 14.30% | 8.00%
Fair value of plan assets |  |  | $ 1,962.3 | $ 2,204.4 | $ 2,329.8 |
Other Pension Plans, Defined Benefit [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Estimated employer contributions in next 12 months |  |  | 10.0 |  |  |
Other Postretirement Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Projected Retirement Benefit Expense In Next 12 months |  |  | $ 34.0 |  |  |
Assumed increase in per capita cost of covered benefits in next 12 months |  |  | 8.00% |  |  |
Assumed ultimate health care cost trend rate |  |  | 4.50% |  |  |
Year that ultimate trend rate is reached |  |  | 2038 |  |  |
Expected long-term rate of return on assets |  |  | 4.00% | 8.30% | 8.30% |
Fair value of plan assets |  |  | $ 1.8 | $ 2.9 | $ 4.0 |
Private equity [Member] | Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Fair value of plan assets |  |  | 201.2 | 172.6 |  |
Fair Value, Inputs, Level 3 [Member] | Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Fair value of plan assets |  |  | 800.2 | 809.7 | 655.3 |
Fair Value, Inputs, Level 3 [Member] | Private equity [Member] | Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Fair value of plan assets |  |  | 201.2 | 172.6 | 123.0 |
Fair Value, Inputs, Level 3 [Member] | Private equity [Member] | Other Postretirement Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Fair value of plan assets |  |  | $ 1.8 |  |  |
Other Postretirement Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Other postretirement benefit costs for a defined contribution plan |  |  |  | $ 2.6 | $ 4.6 |
Forecast [Member] | Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Expected long-term rate of return on assets |  | 8.00% |  |  |  |
Forecast [Member] | Other Postretirement Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Expected long-term rate of return on assets |  | 4.00% |  |  |  |
MultiemployerPlan1 [Member] | Pension Benefits [Member] |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |
Percent of Current Year Contributions to Plan that Company Contributions Exceed |  |  |  | 5.00% |  |

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- Definition Defined Benefit Plan Actuarial Net Gains Losses Mortality Change + References No definition available. + Details
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- Definition For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503844 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition The amount of employer securities or securities of parties related to the employer that are included in plan assets. + 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 (n) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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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 to provide for the benefits included in the benefit obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Expected Long-Term Rate of Return on Plan Assets -URI http://asc.fasb.org/extlink&oid=6512046 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Health Care Cost Trend Rate -URI http://asc.fasb.org/extlink&oid=6514820 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition The number of employer shares or related party shares included in plan assets. + 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 (n) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest 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 (g) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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