Reclassifications From Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified From Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
General and administrative expenses	$ 247	$ 246	$ 221
Provision (benefit) for income taxes	(29)	(2,005)	525
Net Income (Loss)	(2,643)	$ (4,556)	$ 924
Reclassification from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income (Loss)	13
Pension And Other Postretirement [Member] | Reclassification from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
General and administrative expenses	21
Provision (benefit) for income taxes	8
Net Income (Loss)	$ 13