Stockholders' Equity Narrative) (Details) - USD ($) $ in Millions		8 Months Ended	9 Months Ended
	Aug. 31, 2017	Aug. 31, 2017	Sep. 30, 2016	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Shares	87,000,000	87,000,000
Predecessor
Equity, Class of Treasury Stock [Line Items]
Excess of cost of treasury stock over par value		$ 0	$ 3
Treasury Stock, Shares				87,041,000
Retained Earnings [Member] | Predecessor
Equity, Class of Treasury Stock [Line Items]
Excess of cost of treasury stock over par value	$ 5,657
Additional Paid-in Capital [Member] | Predecessor
Equity, Class of Treasury Stock [Line Items]
Excess of cost of treasury stock over par value	$ 1,044