Reclassifications From Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified From Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
General and administrative expenses	$ 61	$ 60	$ 171	$ 188
Provision (benefit) for income taxes	(20)	(1,088)	(20)	(1,532)
Net Loss	$ (708)	$ (1,739)	(2,433)	$ (2,449)
Pension And Other Postretirement [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
General and administrative expenses			2
Provision (benefit) for income taxes			1
Net Loss			$ 1