Reorganization Expense (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended	9 Months Ended
	Jul. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Sep. 30, 2018
Reorganization Items, net [Abstract]
Gain on reorganization adjustments	$ (1,254)	$ 0		$ (1,254)
Gain on fresh start adjustments	(2,007)	0		(2,007)
Debtor Reorganization Items, Other Expense (Income)				104
Success and other fees recognized at emergence	(39)			39
Debtor Reorganization Items, Debtor-in-Possession Facility Financing Costs				13
Reorganization Items	$ (3,261)	$ 0	$ 0	$ (3,105)	$ 0