Stockholders' Equity Share Buyback Program (Details) - Predecessor [Member] - USD ($) $ in Millions	6 Months Ended	8 Months Ended	12 Months Ended	23 Months Ended
	Dec. 31, 2016	Aug. 31, 2017	Dec. 31, 2016	Dec. 31, 2016	Jan. 21, 2015
Equity, Class of Treasury Stock [Line Items]
Shares Repurchased and Retired During Period			(13,152,000)
Payments for Repurchase of Common Stock		$ 0	$ 916
2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
2015 Share Buy Back Announcement					$ 4,000
Shares Repurchased and Retired During Period	13,200,000		48,200,000
Payments for Repurchase of Common Stock	$ 916			$ 2,916