Income Taxes - Allocation of Income Tax Expense (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended		10 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Oct. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax expense in the consolidated statements of operations:
Attributable to income	$ 234	$ 16	$ (40)
Member's/Stockholders' equity:
Tax effect of the change in accumulated other comprehensive loss	$ 17
Predecessor
Income tax expense in the consolidated statements of operations:
Attributable to income				$ 268	$ 165	$ (3,150)
Member's/Stockholders' equity:
Tax effect of the change in accumulated other comprehensive loss				$ 49	$ (43)	$ (11)