Stockholders' Equity Stockholder's Equity (Schedule of tax benefit (expense) on net activity) (Details) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Comprehensive Income (Loss), Tax	$ (51)	$ 404	$ (112)	$ 806
Pension Plan [Member]
Other Comprehensive Income (Loss), Tax	(54)	357	(114)	708
Other Post Employment Benefit Plans [Member]
Other Comprehensive Income (Loss), Tax	(2)	58	(4)	119
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other Comprehensive Income (Loss), Tax	$ 5	$ (11)	$ 6	$ (21)