Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ (3,847)	$ (2,621)
Other comprehensive income (loss) before reclassifications	(295)	(121)
Amounts reclassified from accumulated other comprehensive income	52	34
Other comprehensive (loss) income, net of tax	(243)	(87)
Balance, end of period	(4,090)	(2,708)
Unrealized Investment Gains [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	5	5
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive (loss) income, net of tax	0	0
Balance, end of period	5	5
Pension/Postretirement Plans Gains (Losses) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(3,393)	(2,682)
Other comprehensive income (loss) before reclassifications	128	(199)
Amounts reclassified from accumulated other comprehensive income	52	34
Other comprehensive (loss) income, net of tax	180	(165)
Balance, end of period	(3,213)	(2,847)
Foreign Currency Translation Adjustments [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(459)	56
Other comprehensive income (loss) before reclassifications	(423)	78
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive (loss) income, net of tax	(423)	78
Balance, end of period	$ (882)	$ 134