Stockholders' Equity Share Buyback Program (Details) - Predecessor [Member] - USD ($) $ in Millions	6 Months Ended	8 Months Ended	12 Months Ended		23 Months Ended	43 Months Ended
	Dec. 31, 2016	Aug. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Aug. 31, 2017	Jan. 21, 2015	Jan. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Shares Repurchased and Retired During Period			(13,152,000)	(39,564,000)
Payments for Repurchase of Common Stock		$ 0	$ 916	$ 2,353
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
2014 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount								$ 5,000
Shares Repurchased and Retired During Period						34,700,000
Payments for Repurchase of Common Stock						$ 2,353
Year ended December 31, 2015 [Member] | 2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount							$ 2,000
Year ended December 31, 2015 [Member] | 2014 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Shares Repurchased and Retired During Period				4,600,000
Payments for Repurchase of Common Stock				$ 353