Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications		$ 117
Amounts reclassified from accumulated other comprehensive income		50
Other comprehensive (loss) income, net of tax	$ (204)	167	$ (81)	$ (76)
Balance, ending of period		(3,923)		(3,923)
Unrealized Investment Gains
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	6	5	6	5
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income, net of tax	0	0	0	0
Balance, ending of period	6	5	6	5
Pension/Postretirement Plans Gains (Losses)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(3,014)	(3,213)	(3,124)	(3,393)
Other comprehensive income (loss) before reclassifications	98	(126)	178	2
Amounts reclassified from accumulated other comprehensive income	31	50	61	102
Other comprehensive (loss) income, net of tax	129	(76)	239	104
Balance, ending of period	(2,885)	(3,289)	(2,885)	(3,289)
Foreign Currency Translation Adjustments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(1,089)	(882)	(1,102)	(459)
Other comprehensive income (loss) before reclassifications	(333)	243	(320)	(180)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income, net of tax	(333)	243	(320)	(180)
Balance, ending of period	(1,422)	(639)	(1,422)	(639)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(4,097)	(4,090)	(4,220)	(3,847)
Other comprehensive income (loss) before reclassifications	(235)		(142)	(178)
Amounts reclassified from accumulated other comprehensive income	31		61	102
Other comprehensive (loss) income, net of tax	(204)		(81)	(76)
Balance, ending of period	$ (4,301)	$ (3,923)	$ (4,301)	$ (3,923)