Stockholders' Equity Stockholder's Equity (Schedule of tax benefit (expense) on net activity) (Details) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income (Loss), Tax	$ 12	$ (175)	$ 1,403
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other Comprehensive Income (Loss), Tax	(19)	7	(26)
Pension Plan [Member]
Other Comprehensive Income (Loss), Tax	(163)	(317)	1,274
Other Post Employment Benefit Plans [Member]
Other Comprehensive Income (Loss), Tax	$ 194	$ 135	$ 155