Income Taxes - Income Tax Expense (Benefit) by Current and Deferred (Details) - USD ($) $ in Millions	2 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2017	Oct. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Federal
Current	$ 0		$ 0
Deferred	231		199
State
Current	2		(9)
Deferred	6		28
Foreign
Current	4		30
Deferred	(9)		(52)
Total income tax expense	$ 234		$ 196
Predecessor
Federal
Current		$ 0		$ 0
Deferred		193		177
State
Current		7		4
Deferred		16		27
Foreign
Current		39		41
Deferred		13		(84)
Total income tax expense		$ 268		$ 165