Pension Plans and Other Post Employment Benefit Plans Weighted Average Assumptions used to Determine Benefit Obligations and Periodic Benefit Cost - OPEB (Details) - Other Post Employment Benefits Plan	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount Rate	3.56%		4.23%
Successor [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net Periodic Benefit, Discount Rate	3.62%		3.56%
Predecessor [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount Rate		3.62%		4.03%
Net Periodic Benefit, Discount Rate		4.03%		3.87%