Income Taxes Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended		9 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018
Successor [Member]
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit)	$ 7			$ 55		$ (2,661)
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense		$ 715
Tax Cuts and Jobs Act of 2017, Indirect Impact on Inventory, Income Tax Expense				$ 16
Predecessor [Member]
Operating Loss Carryforwards [Line Items]
Tax benefit related to reduction in company's unrecognized tax benefits					$ 57
Pre tax benefit on associated accrued interest reversals					50
Continuing Operations [Member] | Predecessor [Member]
Operating Loss Carryforwards [Line Items]
Tax benefit related to reduction in company's unrecognized tax benefits					53
Pre tax benefit on associated accrued interest reversals					47
Discontinued Operations [Member] | Predecessor [Member]
Operating Loss Carryforwards [Line Items]
Tax benefit related to reduction in company's unrecognized tax benefits					4
Pre tax benefit on associated accrued interest reversals					$ 3
2016 RTA [Member] | Predecessor [Member]
Operating Loss Carryforwards [Line Items]
Tax expense associated with the elimination of the U.S. domestic manufacturing deduction			$ 29