Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ (4,090)	$ (2,708)	$ (3,847)	$ (2,621)
Other comprehensive income (loss) before reclassifications	117	68	(178)	(53)
Amounts reclassified from accumulated other comprehensive income	50	33	102	67
Other comprehensive (loss) income, net of tax	167	101	(76)	14
Balance, end of period	(3,923)	(2,607)	(3,923)	(2,607)
Unrealized Investment Gains [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	5	5	5	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, end of period	5	5	5	5
Pension/Postretirement Plans Gains (Losses) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(3,213)	(2,847)	(3,393)	(2,682)
Other comprehensive income (loss) before reclassifications	(126)	(69)	2	(268)
Amounts reclassified from accumulated other comprehensive income	50	33	102	67
Other comprehensive (loss) income, net of tax	(76)	(36)	104	(201)
Balance, end of period	(3,289)	(2,883)	(3,289)	(2,883)
Foreign Currency Translation Adjustments [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(882)	134	(459)	56
Other comprehensive income (loss) before reclassifications	243	137	(180)	215
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive (loss) income, net of tax	243	137	(180)	215
Balance, end of period	$ (639)	$ 271	$ (639)	$ 271