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Pension and Savings Plans Weighted-average Assumptions Used to Determine Net Periodic Benefit Cost (Details) - Pension Plan | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Apr. 01, 2017 | Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Successor |  |  |  |  |
Weighted-average assumptions used to determine benefit obligations |  |  |  |  |
Discount rate |  | 3.70% | 4.35% | 3.70% |
Measurement date | Dec. 31, 2018 |  |  |  | Dec. 31, 2017
Weighted-average assumptions used to determine net periodic benefit cost |  |  |  |  |
Discount rate |  | 4.10% | 3.70% |  |
Expected long-term return on plan assets | 5.65% | 5.90% | 5.65% | 4.20% |
Predecessor |  |  |  |  |
Weighted-average assumptions used to determine net periodic benefit cost |  |  |  |  |
Discount rate | 4.15% |  |  |  | 4.55%
Expected long-term return on plan assets | 5.90% |  |  |  | 6.00%

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- Definition Measurement date at which the weighted-average assumptions are used to determine the benefit obligations as of the end of each year. + 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=82843861&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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=82843861&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://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=82843861&loc=d3e1928-114920 + Details
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