Pension Plans and Other Post Employment Benefit Plans Components of net periodic benefit cost (credit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 34
Interest Cost	190
Expected return on plan assets	(303)
Amortization of unrecognized loss	0
Amortization of prior service benefit	0
Net periodic benefit (credit) cost	(79)
Successor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	2
Interest Cost	21
Expected return on plan assets	0
Amortization of unrecognized loss	0
Amortization of prior service benefit	0
Net periodic benefit (credit) cost	23
Predecessor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost		$ 33
Interest Cost		195
Expected return on plan assets		(308)
Amortization of unrecognized loss		190
Amortization of prior service benefit		(1)
Net periodic benefit (credit) cost		109
Predecessor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost		2
Interest Cost		22
Expected return on plan assets		0
Amortization of unrecognized loss		23
Amortization of prior service benefit		(17)
Net periodic benefit (credit) cost		30
Discontinued Operations [Member] | Successor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost	0
Discontinued Operations [Member] | Successor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost	0
Discontinued Operations [Member] | Predecessor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost		1
Discontinued Operations [Member] | Predecessor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost		0
Continuing Operations [Member] | Successor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost	(79)
Continuing Operations [Member] | Successor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost	$ 23
Continuing Operations [Member] | Predecessor [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost		108
Continuing Operations [Member] | Predecessor [Member] | Other Post Employment Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit (credit) cost		$ 30