| General Discussion of Pension and Other Postretirement Benefits [Abstract] | Period [Axis] |
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2016-01-01 - 2016-12-31 |
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General Discussion of Pension and Other Postretirement Benefits [Abstract] | |
Schedule of Changes in Projected Benefit Obligations [Table Text Block] | Changes in the projected benefit obligations and plan assets and the funded status of the plans follow (in millions): | | | | | | | | | | | | | | | | | | Defined Benefit Pension Plans | | Postretirement Health and Life Benefit Plans | | Year Ended December 31, | | Year Ended December 31, | | 2016 | | 2015 | | 2016 | | 2015 | Changes in Benefit Obligations: | | | | | | | | Obligations at beginning of period | $ | 832.8 |
| | $ | 961.4 |
| | $ | 203.5 |
| | $ | 237.7 |
| Actuarial (gains) losses, net | 19.1 |
| | (55.2 | ) | | (9.2 | ) | | (30.2 | ) | Service costs | 3.8 |
| | 5.8 |
| | — |
| | 0.2 |
| Interest costs | 35.4 |
| | 36.9 |
| | 8.2 |
| | 8.8 |
| Benefits paid | (60.9 | ) | | (62.1 | ) | | (13.3 | ) | | (13.1 | ) | Lump sum benefits paid | (12.2 | ) | | (50.6 | ) | | — |
| | — |
| Less federal subsidy on benefits paid | — |
| | — |
| | — |
| | 0.1 |
| Plan change | — |
| | — |
| | 3.6 |
| | — |
| Administrative expenses paid | (3.4 | ) | | (3.4 | ) | | — |
| | — |
| Obligations at end of period | 814.6 |
| | 832.8 |
| | 192.8 |
| | 203.5 |
| Changes in Plan Assets: | | | | | | | | Fair value of plan assets at beginning of period | 656.3 |
| | 772.4 |
| | 13.8 |
| | 26.3 |
| Actual return on plan assets | 50.2 |
| | (8.0 | ) | | 0.5 |
| | 0.4 |
| Company contributions | 4.1 |
| | 8.0 |
| | 6.7 |
| | 0.2 |
| Benefits paid | (60.9 | ) | | (62.1 | ) | | (13.3 | ) | | (13.1 | ) | Lump sum benefits paid | (12.2 | ) | | (50.6 | ) | | — |
| | — |
| Administrative expenses paid | (3.4 | ) | | (3.4 | ) | | — |
| | — |
| Fair value of plan assets at end of period | 634.1 |
| | 656.3 |
| | 7.7 |
| | 13.8 |
| (Unfunded) status at end of period | (180.5 | ) | | (176.5 | ) | | (185.1 | ) | | (189.7 | ) | | | | | | | | | Amounts recognized in assets and liabilities: | | | | | | | | Current liabilities | $ | (0.6 | ) | | $ | (4.2 | ) | | (13.8 | ) | | (5.4 | ) | Noncurrent liabilities | (179.9 | ) | | (172.3 | ) | | (171.3 | ) | | (184.3 | ) | | $ | (180.5 | ) | | $ | (176.5 | ) | | $ | (185.1 | ) | | $ | (189.7 | ) | Amounts in accumulated other comprehensive income (loss), pre-tax: | | | | | | | | Prior service cost (credit) | $ | — |
| | $ | — |
| | $ | (2.6 | ) | | $ | (6.6 | ) | | | | | | | | | Discount rate used to determine benefit obligations at end of period: | 4.1% | | 4.5% | | 3.9% | | 4.2% |
|
Schedule of Net Benefit Costs [Table Text Block] | Components of Net Periodic Benefit Costs and Other Amounts Recognized in Other Comprehensive Loss (in millions) | | | | | | | | | | | | | | | | | | Defined Benefit Pension Plans | | Postretirement Health and Life Benefit Plans | | Year Ended December 31, | | Year Ended December 31, | | 2016 | | 2015 | | 2016 | | 2015 | Net Periodic Benefit Costs | | | | | | | | Service costs | $ | 3.8 |
| | $ | 5.8 |
| | $ | — |
| | $ | 0.2 |
| Interest costs | 35.4 |
| | 36.9 |
| | 8.2 |
| | 8.8 |
| Expected return on plan assets (gains) | (42.0 | ) | | (47.4 | ) | | (0.3 | ) | | (0.8 | ) | Actuarial (gains) losses, net | 10.9 |
| | 0.2 |
| | (9.5 | ) | | (29.8 | ) | Amortization of prior service costs (credits), net | — |
| | — |
| | (0.3 | ) | | (0.3 | ) | Net periodic benefit costs (credits) | $ | 8.1 |
| | $ | (4.5 | ) | | $ | (1.9 | ) | | $ | (21.9 | ) |
| | | | | | | | | | | | | | | | | Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) | | | | | | | | Net prior service costs (credits) | — |
| | — |
| | 3.6 |
| | — |
| Amortization of prior service (costs) credits, net | — |
| | — |
| | 0.3 |
| | 0.3 |
| Total (gain) loss recognized in other comprehensive income (loss), pre-tax | $ | — |
| | $ | — |
| | $ | 3.9 |
| | $ | 0.3 |
| Total recognized in net periodic benefit costs (income) and other comprehensive income (loss), pre-tax | $ | 8.1 |
| | $ | (4.5 | ) | | $ | 2.0 |
| | $ | (21.6 | ) |
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Schedule of Assumptions Used [Table Text Block] | | | | | | | | | | | Defined Benefit Pension Plans | | Postretirement Health and Life Benefit Plans | | Year Ended December 31, | | Year Ended December 31, | | 2016 | | 2015 | | 2016 | | 2015 | Assumptions used to determine net periodic benefit costs: | | | | | | | | Discount rate | 4.1% | | 4.5% | | 3.9% | | 4.2% | Expected return on plan assets | 6.8% | | 6.8% | | 5.0% | | 5.3% |
|
Schedule of Health Care Cost Trend Rates [Table Text Block] | Healthcare cost trend rates used to measure postretirement health benefit obligations follow: | | | | | | December 31, | | 2016 | | 2015 | Healthcare cost trend rate for the following year | 7% | | 7.5% | Long-term rate that the healthcare cost trend rate gradually declines to | 5% | | 5% | Year that the healthcare cost trend rate is expected to reach the long-term rate | 2021 | | 2021 |
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Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] | A one-percentage-point change in the assumed healthcare cost trend rates would have an effect on the postretirement health benefit obligation and costs of the Successor Company, as follows (in millions): | | | | | | | | | | One Percentage Point | | Increase | | Decrease | Postretirement health benefit obligation | $ | 4.0 |
| | $ | (3.8 | ) | Net periodic benefit costs (service and interest cost components only) | $ | 0.3 |
| | $ | (0.3 | ) |
|
Schedule of Allocation of Plan Assets [Table Text Block] | The allocation of plan assets between equity and debt securities and the target allocation range by asset category follows: | | | | | | | | | | | | December 31, | | | | 2016 | | 2015 | | 2017 Target | Defined Benefit Pension Plans: | | | | | | | | Equity securities | 41 | % | | 47 | % | | 40 | - | 60% | Debt securities | 59 |
| | 53 |
| | 40 | - | 60 | | 100 | % | | 100 | % | | | | | Postretirement Health and Life Benefit Plans: | | | | | | | | Equity securities | 100 | % | | 64 | % | | 85 | - | 100% | Debt securities | 0 |
| | 36 |
| | 0 | - | 15 | | 100 | % | | 100 | % | | | | |
Plan assets are measured at fair value. Following are the plan investments as of December 31, 2016, and December 31, 2015, categorized by the fair value hierarchy levels described in Note 10, Fair Value Measurements, (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit Pension Plans | | Level 1 | | Level 2 | | Level 3 | | Total | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | U.S. government securities | $ | — |
| | $ | — |
| | $ | 84.7 |
| | $ | 61.8 |
| | $ | — |
| | $ | — |
| | $ | 84.7 |
| | $ | 61.8 |
| Corporate debt | — |
| | — |
| | 217.0 |
| | 206.9 |
| | — |
| | — |
| | 217.0 |
| | 206.9 |
| Municipal bonds | — |
| | — |
| | 6.2 |
| | 6.8 |
| | — |
| | — |
| | 6.2 |
| | 6.8 |
| Mortgage and asset backed securities | — |
| | — |
| | 5.4 |
| | — |
| | — |
| | — |
| | 5.4 |
| | — |
| Fair value of investments by hierarchy level | $ | — |
| | $ | — |
| | $ | 313.3 |
| | $ | 275.5 |
| | $ | — |
| | $ | — |
| | $ | 313.3 |
| | $ | 275.5 |
| Investments measured at NAV (a) | | | | | | | | | | | | | 318.3 |
| | 377.2 |
| Accrued interest receivable | | | | | | | | | | | | | 3.5 |
| | 3.5 |
| Unsettled transactions | | | | | | | | | | | | | (1.0 | ) | | 0.1 |
| Plan assets | | | | | | | | | | | | | $ | 634.1 |
| | $ | 656.3 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Postretirement Health and Life Benefit Plans | | Level 1 | | Level 2 | | Level 3 | | Total | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | Money market funds | $ | 0.2 |
| | $ | 1.0 |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | 0.2 |
| | $ | 1.0 |
| Bond mutual funds | 7.5 |
| | 4.0 |
| | — |
| | — |
| | — |
| | — |
| | 7.5 |
| | 4.0 |
| Equity mutual funds | — |
| | 8.8 |
| | — |
| | — |
| | — |
| | — |
| | — |
| | 8.8 |
| Fair value of investments by hierarchy level | $ | 7.7 |
| | $ | 13.8 |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | 7.7 |
| | $ | 13.8 |
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(a) Equity, bond and money market investments held in collective trusts are valued based on the net asset value (“NAV”) provided by the administrator of the funds. The NAV for each fund is based on the underlying assets owned by the fund, less any expenses accrued against the fund, divided by the number of fund shares outstanding. While the underlying investments are traded on an exchange, the funds are not. Fair values for the collective trust investments are measured using the NAVs as a practical expedient and are not categorized in the fair value hierarchy. |
Schedule of Expected Benefit Payments [Table Text Block] | Estimated future benefit plan payments follow (in millions): | | | | | | | | | | Defined Benefit Pension Plans | | Postretirement Health and Life Benefit Plans | 2017 | $ | 60.4 |
| | $ | 21.5 |
| 2018 | 59.4 |
| | 20.4 |
| 2019 | 58.0 |
| | 19.0 |
| 2020 | 56.1 |
| | 17.2 |
| 2021 | 55.0 |
| | 15.8 |
| 2022 to 2026 | 258.9 |
| | 61.3 |
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